haiku-beta6/src/servers/app/drawing/DrawingEngine.cpp

/*
 * Copyright 2001-2005, Haiku, Inc.
 * Distributed under the terms of the MIT License.
 *
 * Authors:
 *		Stephan Aßmus <[email protected]>
 */

#include "DrawingEngine.h"

#include <stdio.h>
#include <algo.h>
#include <stack.h>

#include "HWInterface.h"
#include "DrawState.h"
#include "Painter.h"
#include "PNGDump.h"
#include "ServerBitmap.h"
#include "RenderingBuffer.h"

#include "frame_buffer_support.h"

// make_rect_valid
static inline void
make_rect_valid(BRect& rect)
{
	if (rect.left > rect.right) {
		float temp = rect.left;
		rect.left = rect.right;
		rect.right = temp;
	}
	if (rect.top > rect.bottom) {
		float temp = rect.top;
		rect.top = rect.bottom;
		rect.bottom = temp;
	}
}

// extend_by_stroke_width
static inline void
extend_by_stroke_width(BRect& rect, const DrawState* context)
{
	// "- 1.0" because if stroke width == 1, we don't need to extend
	float inset = -ceilf(context->PenSize() / 2.0 - 1.0);
	rect.InsetBy(inset, inset);
}


class FontLocker {
	public:
		FontLocker(const DrawState* context)
			:
			fFont(&context->Font())
		{
			fFont->Lock();
		}
		
		FontLocker(const ServerFont* font)
			:
			fFont(font)
		{
			fFont->Lock();
		}

		~FontLocker()
		{
			fFont->Unlock();
		}

	private:
		const ServerFont*	fFont;
};


//	#pragma mark -


// constructor
DrawingEngine::DrawingEngine(HWInterface* interface)
	: fPainter(new Painter()),
	  fGraphicsCard(interface),
	  fAvailableHWAccleration(0)
{
}

// destructor
DrawingEngine::~DrawingEngine()
{
	delete fPainter;
}

// Initialize
status_t
DrawingEngine::Initialize()
{
	status_t err = B_ERROR;
	if (WriteLock()) {
		err = fGraphicsCard->Initialize();
		if (err < B_OK)
			fprintf(stderr, "HWInterface::Initialize() failed: %s\n", strerror(err));
		WriteUnlock();
	}
	return err;
}

// Shutdown
void
DrawingEngine::Shutdown()
{
}

// Update
void
DrawingEngine::Update()
{
	if (Lock()) {
		fPainter->AttachToBuffer(fGraphicsCard->DrawingBuffer());
		// available HW acceleration might have changed
		fAvailableHWAccleration = fGraphicsCard->AvailableHWAcceleration();
		Unlock();
	}
}


void
DrawingEngine::SetHWInterface(HWInterface* interface)
{
	fGraphicsCard = interface;
}

// #pragma mark -

void
DrawingEngine::ConstrainClippingRegion(const BRegion* region)
{
	if (Lock()) {
		if (!region) {
//			BRegion empty;
//			fPainter->ConstrainClipping(empty);
			if (RenderingBuffer* buffer = fGraphicsCard->DrawingBuffer()) {
				BRegion all;
				all.Include(BRect(0, 0, buffer->Width() - 1, buffer->Height() - 1));
				fPainter->ConstrainClipping(all);
			}
		} else {
			fPainter->ConstrainClipping(*region);
		}
		Unlock();
	}
}

// CopyRegion() does a topological sort of the rects in the
// region. The algorithm was suggested by Ingo Weinhold.
// It compares each rect with each rect and builds a tree
// of successors so we know the order in which they can be copied.
// For example, let's suppose these rects are in a BRegion:
//                        ************
//                        *    B     *
//                        ************
//      *************
//      *           *
//      *     A     ****************
//      *           **             *
//      **************             *
//                   *     C       *
//                   *             *
//                   *             *
//                   ***************
// When copying stuff from LEFT TO RIGHT, TOP TO BOTTOM, the
// result of the sort will be C, A, B. For this direction, we search
// for the rects that have no neighbors to their right and to their
// bottom, These can be copied without drawing into the area of
// rects yet to be copied. If you move from RIGHT TO LEFT, BOTTOM TO TOP,
// you go look for the ones that have no neighbors to their top and left.
//
// Here I draw some rays to illustrate LEFT TO RIGHT, TOP TO BOTTOM:
//                        ************
//                        *    B     *
//                        ************
//      *************
//      *           *
//      *     A     ****************-----------------
//      *           **             *
//      **************             *
//                   *     C       *
//                   *             *
//                   *             *
//                   ***************
//                   |
//                   |
//                   |
//                   |
// There are no rects in the area defined by the rays to the right
// and bottom of rect C, so that's the one we want to copy first
// (for positive x and y offsets).
// Since A is to the left of C and B is to the top of C, The "node"
// for C will point to the nodes of A and B as its "successors". Therefor,
// A and B will have an "indegree" of 1 for C pointing to them. C will
// have and "indegree" of 0, because there was no rect to which C
// was to the left or top of. When comparing A and B, neither is left
// or top from the other and in the sense that the algorithm cares about.

// NOTE: comparisson of coordinates assumes that rects don't overlap
// and don't share the actual edge either (as is the case in BRegions).

struct node {
			node()
			{
				pointers = NULL;
			}
			node(const BRect& r, int32 maxPointers)
			{
				init(r, maxPointers);
			}
			~node()
			{
				delete [] pointers;
			}

	void	init(const BRect& r, int32 maxPointers)
			{
				rect = r;
				pointers = new node*[maxPointers];
				in_degree = 0;
				next_pointer = 0;
			}

	void	push(node* node)
			{
				pointers[next_pointer] = node;
				next_pointer++;
			}
	node*	top()
			{
				return pointers[next_pointer];
			}
	node*	pop()
			{
				node* ret = top();
				next_pointer--;
				return ret;
			}

	BRect	rect;
	int32	in_degree;
	node**	pointers;
	int32	next_pointer;
};

bool
is_left_of(const BRect& a, const BRect& b)
{
	return (a.right < b.left);
}
bool
is_above(const BRect& a, const BRect& b)
{
	return (a.bottom < b.top);
}

// CopyRegion
void
DrawingEngine::CopyRegion(/*const*/ BRegion* region,
						  int32 xOffset, int32 yOffset)
{
	// NOTE: Write locking because we might use HW acceleration.
	// This needs to be investigated, I'm doing this because of
	// gut feeling.
	if (WriteLock()) {
		BRect frame = region->Frame();
		frame = frame | frame.OffsetByCopy(xOffset, yOffset);
		fGraphicsCard->HideSoftwareCursor(frame);

		int32 count = region->CountRects();

		// TODO: make this step unnecessary
		// (by using different stack impl inside node)
		node nodes[count];
		for (int32 i= 0; i < count; i++) {
			nodes[i].init(region->RectAt(i), count);
		}

		for (int32 i = 0; i < count; i++) {
			BRect a = region->RectAt(i);
			for (int32 k = i + 1; k < count; k++) {
				BRect b = region->RectAt(k);
				int cmp = 0;
				// compare horizontally
				if (xOffset > 0) {
					if (is_left_of(a, b)) {
						cmp -= 1;
					} else if (is_left_of(b, a)) {
						cmp += 1;
					}
				} else if (xOffset < 0) {
					if (is_left_of(a, b)) {
						cmp += 1;
					} else if (is_left_of(b, a)) {
						cmp -= 1;
					}
				}
				// compare vertically
				if (yOffset > 0) {
					if (is_above(a, b)) {
						cmp -= 1;	
					} else if (is_above(b, a)) {
						cmp += 1;
					}
				} else if (yOffset < 0) {
					if (is_above(a, b)) {
						cmp += 1;
					} else if (is_above(b, a)) {
						cmp -= 1;
					}
				}
				// add appropriate node as successor
				if (cmp > 0) {
					nodes[i].push(&nodes[k]);
					nodes[k].in_degree++;
				} else if (cmp < 0) {
					nodes[k].push(&nodes[i]);
					nodes[i].in_degree++;
				}
			}
		}
		// put all nodes onto a stack that have an "indegree" count of zero
		stack<node*> inDegreeZeroNodes;
		for (int32 i = 0; i < count; i++) {
			if (nodes[i].in_degree == 0) {
				inDegreeZeroNodes.push(&nodes[i]);
			}
		}
		// pop the rects from the stack, do the actual copy operation
		// and decrease the "indegree" count of the other rects not
		// currently on the stack and to which the current rect pointed
		// to. If their "indegree" count reaches zero, put them onto the
		// stack as well.

		clipping_rect* sortedRectList = NULL;
		int32 nextSortedIndex = 0;

		if (fAvailableHWAccleration & HW_ACC_COPY_REGION)
			sortedRectList = new clipping_rect[count];

		while (!inDegreeZeroNodes.empty()) {
			node* n = inDegreeZeroNodes.top();
			inDegreeZeroNodes.pop();

			// do the software implementation or add to sorted
			// rect list for using the HW accelerated version
			// later
			if (sortedRectList) {
				sortedRectList[nextSortedIndex].left	= (int32)n->rect.left;
				sortedRectList[nextSortedIndex].top		= (int32)n->rect.top;
				sortedRectList[nextSortedIndex].right	= (int32)n->rect.right;
				sortedRectList[nextSortedIndex].bottom	= (int32)n->rect.bottom;
				nextSortedIndex++;
			} else {
				BRect touched = _CopyRect(n->rect, xOffset, yOffset);
				fGraphicsCard->Invalidate(touched);
			}

			for (int32 k = 0; k < n->next_pointer; k++) {
				n->pointers[k]->in_degree--;
				if (n->pointers[k]->in_degree == 0)
					inDegreeZeroNodes.push(n->pointers[k]);
			}
		}

		// trigger the HW accelerated version if is was available
		if (sortedRectList)
			fGraphicsCard->CopyRegion(sortedRectList, count, xOffset, yOffset);

		delete[] sortedRectList;

		fGraphicsCard->ShowSoftwareCursor();

		WriteUnlock();
	}
}

// InvertRect
void
DrawingEngine::InvertRect(BRect r)
{
	// NOTE: Write locking because we might use HW acceleration.
	// This needs to be investigated, I'm doing this because of
	// gut feeling.
	if (WriteLock()) {
		make_rect_valid(r);
		r = fPainter->ClipRect(r);
		if (r.IsValid()) {
			fGraphicsCard->HideSoftwareCursor(r);

			// try hardware optimized version first
			if (fAvailableHWAccleration & HW_ACC_INVERT_REGION) {
				BRegion region(r);
				region.IntersectWith(fPainter->ClippingRegion());
				fGraphicsCard->InvertRegion(region);
			} else {		
				fPainter->InvertRect(r);

				fGraphicsCard->Invalidate(r);
			}

			fGraphicsCard->ShowSoftwareCursor();
		}

		WriteUnlock();
	}
}

// DrawBitmap
void
DrawingEngine::DrawBitmap(ServerBitmap *bitmap,
						  const BRect &source, const BRect &dest,
						  const DrawState *d)
{
	if (Lock()) {
		BRect clipped = fPainter->ClipRect(dest);
		if (clipped.IsValid()) {
			fGraphicsCard->HideSoftwareCursor(clipped);
	
			fPainter->SetDrawState(d);
			fPainter->DrawBitmap(bitmap, source, dest);
	
			fGraphicsCard->Invalidate(clipped);
			fGraphicsCard->ShowSoftwareCursor();
		}

		Unlock();
	}
}

// DrawArc
void
DrawingEngine::DrawArc(BRect r, const float &angle,
					   const float &span, const DrawState *d,
					   bool filled)
{
	if (Lock()) {
		make_rect_valid(r);
		BRect clipped(r);
		if (!filled)
			extend_by_stroke_width(clipped, d);
		clipped = fPainter->ClipRect(r);
		if (clipped.IsValid()) {
			fGraphicsCard->HideSoftwareCursor(clipped);
	
			fPainter->SetDrawState(d);
	
			float xRadius = r.Width() / 2.0;
			float yRadius = r.Height() / 2.0;
			BPoint center(r.left + xRadius,
						  r.top + yRadius);

			if (filled)	
				fPainter->FillArc(center, xRadius, yRadius, angle, span);
			else
				fPainter->StrokeArc(center, xRadius, yRadius, angle, span);
	
			fGraphicsCard->Invalidate(clipped);
			fGraphicsCard->ShowSoftwareCursor();
		}

		Unlock();
	}
}

// DrawBezier
void
DrawingEngine::DrawBezier(BPoint *pts, const DrawState *d, bool filled)
{
	if (Lock()) {
		fGraphicsCard->HideSoftwareCursor();

		fPainter->SetDrawState(d);
		BRect touched = filled ? fPainter->FillBezier(pts)
							   : fPainter->StrokeBezier(pts);

		fGraphicsCard->Invalidate(touched);
		fGraphicsCard->ShowSoftwareCursor();

		Unlock();
	}
}

// DrawEllipse
void
DrawingEngine::DrawEllipse(BRect r, const DrawState *d, bool filled)
{
	if (Lock()) {
		make_rect_valid(r);
		BRect clipped = r;
		if (!filled)
			extend_by_stroke_width(clipped, d);
		clipped = fPainter->ClipRect(clipped);
		if (clipped.IsValid()) {
			fGraphicsCard->HideSoftwareCursor(r);
	
			fPainter->SetDrawState(d);
	
			float xRadius = r.Width() / 2.0;
			float yRadius = r.Height() / 2.0;
			BPoint center(r.left + xRadius,
						  r.top + yRadius);

			if (filled)
				fPainter->FillEllipse(center, xRadius, yRadius);
			else
				fPainter->StrokeEllipse(center, xRadius, yRadius);
	
			fGraphicsCard->Invalidate(clipped);
			fGraphicsCard->ShowSoftwareCursor();
		}

		Unlock();
	}
}

// DrawPolygon
void
DrawingEngine::DrawPolygon(BPoint* ptlist, int32 numpts,
						   BRect bounds, const DrawState* d,
						   bool filled, bool closed)
{
	if (Lock()) {
		make_rect_valid(bounds);
		if (!filled)
			extend_by_stroke_width(bounds, d);
		bounds = fPainter->ClipRect(bounds);
		if (bounds.IsValid()) {
			fGraphicsCard->HideSoftwareCursor(bounds);
	
			fPainter->SetDrawState(d);
			if (filled)
				fPainter->FillPolygon(ptlist, numpts);
			else
				fPainter->StrokePolygon(ptlist, numpts, closed);
	
			fGraphicsCard->Invalidate(bounds);
			fGraphicsCard->ShowSoftwareCursor();
		}

		Unlock();
	}
}

// StrokeRect
// 
// this function is used to draw a one pixel wide rect
void
DrawingEngine::StrokeRect(BRect r, const RGBColor &color)
{
	if (Lock()) {
		make_rect_valid(r);
		BRect clipped = fPainter->ClipRect(r);
		if (clipped.IsValid()) {
			fGraphicsCard->HideSoftwareCursor(clipped);
	
			fPainter->StrokeRect(r, color.GetColor32());
	
			fGraphicsCard->Invalidate(fPainter->ClipRect(BRect(r.left, r.top,
															   r.right, r.top)));
			fGraphicsCard->Invalidate(fPainter->ClipRect(BRect(r.left, r.top + 1,
															   r.left, r.bottom - 1)));
			fGraphicsCard->Invalidate(fPainter->ClipRect(BRect(r.right, r.top + 1,
															   r.right, r.bottom - 1)));
			fGraphicsCard->Invalidate(fPainter->ClipRect(BRect(r.left, r.bottom,
															   r.right, r.bottom)));
			fGraphicsCard->ShowSoftwareCursor();
		}

		Unlock();
	}
}

// FillRect
void
DrawingEngine::FillRect(BRect r, const RGBColor& color)
{
	// NOTE: Write locking because we might use HW acceleration.
	// This needs to be investigated, I'm doing this because of
	// gut feeling.
	if (WriteLock()) {
		make_rect_valid(r);
		r = fPainter->ClipRect(r);
		if (r.IsValid()) {
			fGraphicsCard->HideSoftwareCursor(r);
	
			// try hardware optimized version first
			if (fAvailableHWAccleration & HW_ACC_FILL_REGION) {
				BRegion region(r);
				region.IntersectWith(fPainter->ClippingRegion());
				fGraphicsCard->FillRegion(region, color);
			} else {
				fPainter->FillRect(r, color.GetColor32());
		
				fGraphicsCard->Invalidate(r);
			}
	
			fGraphicsCard->ShowSoftwareCursor();
		}

		WriteUnlock();
	}
}

// StrokeRect
void
DrawingEngine::StrokeRect(BRect r, const DrawState *d)
{
	if (Lock()) {
		// support invalid rects
		make_rect_valid(r);
		BRect clipped(r);
		extend_by_stroke_width(clipped, d);
		clipped = fPainter->ClipRect(clipped);
		if (clipped.IsValid()) {
	
			fGraphicsCard->HideSoftwareCursor(clipped);
	
			fPainter->SetDrawState(d);
			fPainter->StrokeRect(r);
	
			fGraphicsCard->Invalidate(clipped);
			fGraphicsCard->ShowSoftwareCursor();
		}

		Unlock();
	}
}

// FillRect
void
DrawingEngine::FillRect(BRect r, const DrawState *d)
{
	// NOTE: Write locking because we might use HW acceleration.
	// This needs to be investigated, I'm doing this because of
	// gut feeling.
	if (WriteLock()) {
		make_rect_valid(r);
		r = fPainter->ClipRect(r);
		if (r.IsValid()) {
			fGraphicsCard->HideSoftwareCursor(r);

			bool doInSoftware = true;
			// try hardware optimized version first
			if ((fAvailableHWAccleration & HW_ACC_FILL_REGION) != 0
				&& (d->GetDrawingMode() == B_OP_COPY
					|| d->GetDrawingMode() == B_OP_OVER)) {
				if (d->GetPattern() == B_SOLID_HIGH) {
					BRegion region(r);
					region.IntersectWith(fPainter->ClippingRegion());
					fGraphicsCard->FillRegion(region, d->HighColor());
					doInSoftware = false;
				} else if (d->GetPattern() == B_SOLID_LOW) {
					BRegion region(r);
					region.IntersectWith(fPainter->ClippingRegion());
					fGraphicsCard->FillRegion(region, d->LowColor());
					doInSoftware = false;
				}
			}
			if (doInSoftware) {
				fPainter->SetDrawState(d);
				fPainter->FillRect(r);

				fGraphicsCard->Invalidate(r);
			}

			fGraphicsCard->ShowSoftwareCursor();
		}

		WriteUnlock();
	}
}
/*
// StrokeRegion
void
DrawingEngine::StrokeRegion(BRegion& r, const DrawState *d)
{
	if (Lock()) {
		BRect clipped(r.Frame());
		extend_by_stroke_width(clipped, d);
		clipped = fPainter->ClipRect(clipped);
		if (clipped.IsValid()) {
			fGraphicsCard->HideSoftwareCursor(clipped);

			fPainter->SetDrawState(d);

			BRect touched = fPainter->StrokeRect(r.RectAt(0));

			int32 count = r.CountRects();
			for (int32 i = 1; i < count; i++) {
				touched = touched | fPainter->StrokeRect(r.RectAt(i));
			}

			fGraphicsCard->Invalidate(touched);
			fGraphicsCard->ShowSoftwareCursor();
		}

		Unlock();
	}
}
*/
// FillRegion
void
DrawingEngine::FillRegion(BRegion& r, const DrawState *d)
{
	// NOTE: Write locking because we might use HW acceleration.
	// This needs to be investigated, I'm doing this because of
	// gut feeling.
	if (WriteLock()) {
		BRect clipped = fPainter->ClipRect(r.Frame());
		if (clipped.IsValid()) {
			fGraphicsCard->HideSoftwareCursor(clipped);

			bool doInSoftware = true;
			// try hardware optimized version first
			if ((fAvailableHWAccleration & HW_ACC_FILL_REGION) != 0
				&& (d->GetDrawingMode() == B_OP_COPY
					|| d->GetDrawingMode() == B_OP_OVER)) {
				if (d->GetPattern() == B_SOLID_HIGH) {
					r.IntersectWith(fPainter->ClippingRegion());
					fGraphicsCard->FillRegion(r, d->HighColor());
					doInSoftware = false;
				} else if (d->GetPattern() == B_SOLID_LOW) {
					r.IntersectWith(fPainter->ClippingRegion());
					fGraphicsCard->FillRegion(r, d->LowColor());
					doInSoftware = false;
				}
			}

			if (doInSoftware) {
				fPainter->SetDrawState(d);

				BRect touched = fPainter->FillRect(r.RectAt(0));

				int32 count = r.CountRects();
				for (int32 i = 1; i < count; i++) {
					touched = touched | fPainter->FillRect(r.RectAt(i));
				}

				fGraphicsCard->Invalidate(touched);
			}

			fGraphicsCard->ShowSoftwareCursor();
		}

		WriteUnlock();
	}
}


// FillRegion
void
DrawingEngine::FillRegion(BRegion& r, const RGBColor& color)
{
	// NOTE: Write locking because we might use HW acceleration.
	// This needs to be investigated, I'm doing this because of
	// gut feeling.
	// NOTE: region expected to be already clipped correctly!!
	if (WriteLock()) {
		fGraphicsCard->HideSoftwareCursor(r.Frame());

		bool doInSoftware = true;
		// try hardware optimized version first
		if ((fAvailableHWAccleration & HW_ACC_FILL_REGION) != 0) {
			fGraphicsCard->FillRegion(r, color);
			doInSoftware = false;
		}

		if (doInSoftware) {

			int32 count = r.CountRects();
			for (int32 i = 0; i < count; i++) {
				fPainter->FillRectNoClipping(r.RectAt(i), color.GetColor32());
			}
			BRect touched = r.Frame();

			fGraphicsCard->Invalidate(touched);
		}

		fGraphicsCard->ShowSoftwareCursor();

		WriteUnlock();
	}
}


void
DrawingEngine::DrawRoundRect(BRect r, float xrad, float yrad,
	const DrawState* d, bool filled)
{
	if (!Lock())
		return;

	// NOTE: the stroke does not extend past "r" in R5,
	// though I consider this unexpected behaviour.
	make_rect_valid(r);
	BRect clipped = fPainter->ClipRect(r);
	if (clipped.IsValid()) {
		fGraphicsCard->HideSoftwareCursor(clipped);

		fPainter->SetDrawState(d);
		BRect touched = filled ? fPainter->FillRoundRect(r, xrad, yrad)
							   : fPainter->StrokeRoundRect(r, xrad, yrad);

		fGraphicsCard->Invalidate(touched);
		fGraphicsCard->ShowSoftwareCursor();
	}

	Unlock();
}


void
DrawingEngine::DrawShape(const BRect& bounds, int32 opCount,
	const uint32* opList, int32 ptCount, const BPoint* ptList,
	const DrawState* d, bool filled)
{
	if (!Lock())
		return;

	fGraphicsCard->HideSoftwareCursor();

	fPainter->SetDrawState(d);
	BRect touched = fPainter->DrawShape(opCount, opList,
										ptCount, ptList,
										filled);

	fGraphicsCard->Invalidate(touched);
	fGraphicsCard->ShowSoftwareCursor();

	Unlock();
}


void
DrawingEngine::DrawTriangle(BPoint* pts, const BRect& bounds,
	const DrawState* d, bool filled)
{
	if (Lock()) {
		BRect clipped(bounds);
		if (!filled)
			extend_by_stroke_width(clipped, d);
		clipped = fPainter->ClipRect(clipped);
		if (clipped.IsValid()) {
			fGraphicsCard->HideSoftwareCursor(clipped);

			fPainter->SetDrawState(d);
			if (filled)
				fPainter->FillTriangle(pts[0], pts[1], pts[2]);
			else
				fPainter->StrokeTriangle(pts[0], pts[1], pts[2]);

			fGraphicsCard->Invalidate(clipped);
			fGraphicsCard->ShowSoftwareCursor();
		}

		Unlock();
	}
}

// StrokeLine
//
// * this function is only used by Decorators
// * it assumes a one pixel wide line
void
DrawingEngine::StrokeLine(const BPoint &start, const BPoint &end, const RGBColor &color)
{
	if (Lock()) {
		BRect touched(start, end);
		make_rect_valid(touched);
		touched = fPainter->ClipRect(touched);
		fGraphicsCard->HideSoftwareCursor(touched);

		if (!fPainter->StraightLine(start, end, color.GetColor32())) {
			DrawState context;
			context.SetHighColor(color);
			context.SetDrawingMode(B_OP_OVER);
			StrokeLine(start, end, &context);
		} else {
			fGraphicsCard->Invalidate(touched);
		}
		fGraphicsCard->ShowSoftwareCursor();
		Unlock();
	}
}

// StrokeLine
void
DrawingEngine::StrokeLine(const BPoint &start, const BPoint &end, DrawState* context)
{
	if (Lock()) {
		BRect touched(start, end);
		make_rect_valid(touched);
		extend_by_stroke_width(touched, context);
		touched = fPainter->ClipRect(touched);
		if (touched.IsValid()) {
			fGraphicsCard->HideSoftwareCursor(touched);

			fPainter->SetDrawState(context);
			touched = fPainter->StrokeLine(start, end);

			fGraphicsCard->Invalidate(touched);
			fGraphicsCard->ShowSoftwareCursor();
		}

		Unlock();
	}
}

// StrokeLineArray
void
DrawingEngine::StrokeLineArray(int32 numLines,
	const LineArrayData *linedata, const DrawState *d)
{
	if (!d || !linedata || numLines <= 0)
		return;

	if (Lock()) {
		// figure out bounding box for line array
		const LineArrayData *data = (const LineArrayData *)&(linedata[0]);
		BRect touched(min_c(data->pt1.x, data->pt2.x),
					  min_c(data->pt1.y, data->pt2.y),
					  max_c(data->pt1.x, data->pt2.x),
					  max_c(data->pt1.y, data->pt2.y));

		for (int32 i = 1; i < numLines; i++) {
			data = (const LineArrayData *)&(linedata[i]);
			BRect box(min_c(data->pt1.x, data->pt2.x),
					  min_c(data->pt1.y, data->pt2.y),
					  max_c(data->pt1.x, data->pt2.x),
					  max_c(data->pt1.y, data->pt2.y));
			touched = touched | box;
		}
		extend_by_stroke_width(touched, d);
		touched = fPainter->ClipRect(touched);
		if (touched.IsValid()) {
			fGraphicsCard->HideSoftwareCursor(touched);

			data = (const LineArrayData *)&(linedata[0]);

			DrawState context;
			context.SetDrawingMode(d->GetDrawingMode());
			context.SetLowColor(d->LowColor());
			context.SetHighColor(data->color);
			context.SetPenSize(d->PenSize());
				// pen size is already correctly scaled

			fPainter->SetDrawState(&context);

			fPainter->StrokeLine(data->pt1, data->pt2);

			for (int32 i = 1; i < numLines; i++) {
				data = (const LineArrayData *)&(linedata[i]);
				fPainter->SetHighColor(data->color);
				fPainter->StrokeLine(data->pt1, data->pt2);
			}

			fGraphicsCard->Invalidate(touched);
			fGraphicsCard->ShowSoftwareCursor();
		}

		Unlock();
	}
}

// StrokePoint
//
// * this function is only used by Decorators
void
DrawingEngine::StrokePoint(const BPoint& pt, const RGBColor &color)
{
	StrokeLine(pt, pt, color);
}

// StrokePoint
void
DrawingEngine::StrokePoint(const BPoint& pt, DrawState *context)
{
	StrokeLine(pt, pt, context);
}

// #pragma mark -

// DrawString
BPoint
DrawingEngine::DrawString(const char* string, int32 length,
						  const BPoint& pt, DrawState* d,
						  escapement_delta* delta)
{
// TODO: use delta
	BPoint penLocation = pt;
	if (Lock()) {
		FontLocker locker(d);
		fPainter->SetDrawState(d, true);
//bigtime_t now = system_time();
// TODO: BoundingBox is quite slow!! Optimizing it will be beneficial.
// Cursiously, the DrawString after it is actually faster!?!
// TODO: make the availability of the hardware cursor part of the 
// HW acceleration flags and skip all calculations for HideSoftwareCursor
// in case we don't have one.
// TODO: Watch out about penLocation and use Painter::PenLocation() when
// not using BoundindBox anymore.
		BRect b = fPainter->BoundingBox(string, length, pt, &penLocation, delta);
		// stop here if we're supposed to render outside of the clipping
		b = fPainter->ClipRect(b);
		if (b.IsValid()) {
//printf("bounding box '%s': %lld µs\n", string, system_time() - now);
			fGraphicsCard->HideSoftwareCursor(b);

//now = system_time();
			BRect touched = fPainter->DrawString(string, length, pt, delta);
//printf("drawing string: %lld µs\n", system_time() - now);

			fGraphicsCard->Invalidate(touched);
			fGraphicsCard->ShowSoftwareCursor();
		}
		Unlock();
	}
	return penLocation;
}

// StringWidth
float
DrawingEngine::StringWidth(const char* string, int32 length,
						   const DrawState* d, escapement_delta* delta)
{
// TODO: use delta
	float width = 0.0;
//	if (Lock()) {
// NOTE: For now it is enough to block on the
// font style lock, this already prevents multiple
// threads from executing this code and avoids a
// deadlock in case another thread holds the font
// lock already and then tries to lock the drawing
// engine after it is already locked here (race condition)
		FontLocker locker(d);
		width = fPainter->StringWidth(string, length, d);
//		Unlock();
//	}
	return width;
}

// StringWidth
float
DrawingEngine::StringWidth(const char* string, int32 length,
						   const ServerFont& font, escapement_delta* delta)
{
	FontLocker locker(&font);
	DrawState d;
	d.SetFont(font);
	return StringWidth(string, length, &d, delta);
}

// StringHeight
float
DrawingEngine::StringHeight(const char *string, int32 length,
							const DrawState *d)
{
	float height = 0.0;
//	if (Lock()) {
// NOTE: For now it is enough to block on the
// font style lock, this already prevents multiple
// threads from executing this code and avoids a
// deadlock in case another thread holds the font
// lock already and then tries to lock the drawing
// engine after it is already locked here (race condition)
		FontLocker locker(d);
		fPainter->SetDrawState(d, true);
		BPoint dummy1(0.0, 0.0);
		BPoint dummy2(0.0, 0.0);
		height = fPainter->BoundingBox(string, length, dummy1, &dummy2).Height();
//		Unlock();
//	}
	return height;
}

// #pragma mark -

// Lock
bool
DrawingEngine::Lock()
{
	return fGraphicsCard->WriteLock();
}

// Unlock
void
DrawingEngine::Unlock()
{
	fGraphicsCard->WriteUnlock();
}

// WriteLock
bool
DrawingEngine::WriteLock()
{	
	return fGraphicsCard->WriteLock();
}

// WriteUnlock
void
DrawingEngine::WriteUnlock()
{
	fGraphicsCard->WriteUnlock();
}

// #pragma mark -

// DumpToFile
bool
DrawingEngine::DumpToFile(const char *path)
{
	if (Lock()) {
		RenderingBuffer* buffer = fGraphicsCard->DrawingBuffer();
		if (buffer) {
			BRect bounds(0.0, 0.0, buffer->Width() - 1, buffer->Height() - 1);
			SaveToPNG(path, bounds, buffer->ColorSpace(),
					  buffer->Bits(),
					  buffer->BitsLength(),
					  buffer->BytesPerRow());
		}
		Unlock();
	}	
	return true;
}

// DumpToBitmap
ServerBitmap*
DrawingEngine::DumpToBitmap()
{
	return NULL;
}

status_t
DrawingEngine::ReadBitmap(ServerBitmap *bitmap, bool drawCursor, BRect bounds)
{
	if (Lock()) {
		RenderingBuffer *buffer = fGraphicsCard->DrawingBuffer();
		if (!buffer)
			return B_ERROR;

		BRect clip(0, 0, buffer->Width() - 1, buffer->Height() - 1);
		bounds = bounds & clip;
		fGraphicsCard->HideSoftwareCursor(bounds);

		status_t result = bitmap->ImportBits(buffer->Bits(),
			buffer->BitsLength(), buffer->BytesPerRow(), buffer->ColorSpace(),
			bounds.LeftTop(), BPoint(0, 0), bounds.IntegerWidth(),
			bounds.IntegerHeight());

		if (drawCursor) {
			// ToDo: blend the cursor
		}

		fGraphicsCard->ShowSoftwareCursor();
		Unlock();
		return result;
	}

	return B_ERROR;
}

// #pragma mark -

BRect
DrawingEngine::_CopyRect(BRect src, int32 xOffset, int32 yOffset) const
{
	// TODO: assumes drawing buffer is 32 bits (which it currently always is)
	BRect dst;
	RenderingBuffer* buffer = fGraphicsCard->DrawingBuffer();
	if (buffer) {
		BRect clip(0, 0, buffer->Width() - 1, buffer->Height() - 1);

		dst = src;
		dst.OffsetBy(xOffset, yOffset);

		if (clip.Intersects(src) && clip.Intersects(dst)) {
			uint32 bytesPerRow = buffer->BytesPerRow();
			uint8* bits = (uint8*)buffer->Bits();

			// clip source rect
			src = src & clip;
			// clip dest rect
			dst = dst & clip;
			// move dest back over source and clip source to dest
			dst.OffsetBy(-xOffset, -yOffset);
			src = src & dst;

			// calc offset in buffer
			bits += (int32)src.left * 4 + (int32)src.top * bytesPerRow;

			uint32 width = src.IntegerWidth() + 1;
			uint32 height = src.IntegerHeight() + 1;

			_CopyRect(bits, width, height, bytesPerRow, xOffset, yOffset);

			// offset dest again, because it is return value
			dst.OffsetBy(xOffset, yOffset);
		}
	}
	return dst;
}


void
DrawingEngine::_CopyRect(uint8* src, uint32 width, uint32 height,
	uint32 bytesPerRow, int32 xOffset, int32 yOffset) const
{
	// TODO: assumes drawing buffer is 32 bits (which it currently always is)
	int32 xIncrement;
	int32 yIncrement;

	if (yOffset == 0 && xOffset > 0) {
		// copy from right to left
		xIncrement = -1;
		src += (width - 1) * 4;
	} else {
		// copy from left to right
		xIncrement = 1;
	}

	if (yOffset > 0) {
		// copy from bottom to top
		yIncrement = -bytesPerRow;
		src += (height - 1) * bytesPerRow;
	} else {
		// copy from top to bottom
		yIncrement = bytesPerRow;
	}

	uint8* dst = src + yOffset * bytesPerRow + xOffset * 4;

	if (xIncrement == 1) {
		uint8 tmpBuffer[width * 4];
		for (uint32 y = 0; y < height; y++) {
			// NOTE: read into temporary scanline buffer,
			// avoid memcpy because it might be graphics card memory
			gfxcpy32(tmpBuffer, src, width * 4);
			// write back temporary scanline buffer
			// NOTE: **don't read and write over the PCI bus
			// at the same time**
			memcpy(dst, tmpBuffer, width * 4);
// NOTE: this (instead of the two pass copy above) might
// speed up QEMU -> ?!? (would depend on how it emulates
// the PCI bus...)
// TODO: would be nice if we actually knew
// if we're operating in graphics memory or main memory...
//memcpy(dst, src, width * 4);
			src += yIncrement;
			dst += yIncrement;
		}
	} else {
		for (uint32 y = 0; y < height; y++) {
			uint32* srcHandle = (uint32*)src;
			uint32* dstHandle = (uint32*)dst;
			for (uint32 x = 0; x < width; x++) {
				*dstHandle = *srcHandle;
				srcHandle += xIncrement;
				dstHandle += xIncrement;
			}
			src += yIncrement;
			dst += yIncrement;
		}
	}
}