244 lines
9.3 KiB
C++
244 lines
9.3 KiB
C++
/*
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* Copyright 2012 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkSurface_DEFINED
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#define SkSurface_DEFINED
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#include "SkRefCnt.h"
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#include "SkImage.h"
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#include "SkSurfaceProps.h"
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class SkCanvas;
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class SkPaint;
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class GrContext;
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class GrRenderTarget;
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/**
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* SkSurface represents the backend/results of drawing to a canvas. For raster
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* drawing, the surface will be pixels, but (for example) when drawing into
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* a PDF or Picture canvas, the surface stores the recorded commands.
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*
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* To draw into a canvas, first create the appropriate type of Surface, and
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* then request the canvas from the surface.
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*
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* SkSurface always has non-zero dimensions. If there is a request for a new surface, and either
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* of the requested dimensions are zero, then NULL will be returned.
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*/
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class SK_API SkSurface : public SkRefCnt {
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public:
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SK_DECLARE_INST_COUNT(SkSurface)
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/**
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* Create a new surface, using the specified pixels/rowbytes as its
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* backend.
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*
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* If the requested surface cannot be created, or the request is not a
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* supported configuration, NULL will be returned.
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*/
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static SkSurface* NewRasterDirect(const SkImageInfo&, void* pixels, size_t rowBytes,
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const SkSurfaceProps* = NULL);
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/**
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* The same as NewRasterDirect, but also accepts a call-back routine, which is invoked
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* when the surface is deleted, and is passed the pixel memory and the specified context.
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*/
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static SkSurface* NewRasterDirectReleaseProc(const SkImageInfo&, void* pixels, size_t rowBytes,
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void (*releaseProc)(void* pixels, void* context),
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void* context, const SkSurfaceProps* = NULL);
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/**
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* Return a new surface, with the memory for the pixels automatically
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* allocated.
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*
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* If the requested surface cannot be created, or the request is not a
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* supported configuration, NULL will be returned.
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*/
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static SkSurface* NewRaster(const SkImageInfo&, const SkSurfaceProps* = NULL);
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/**
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* Helper version of NewRaster. It creates a SkImageInfo with the
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* specified width and height, and populates the rest of info to match
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* pixels in SkPMColor format.
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*/
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#ifdef SK_SUPPORT_LEGACY_NewRasterPMColor
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static SkSurface* NewRasterPMColor(int width, int height, const SkSurfaceProps* props = NULL) {
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return NewRaster(SkImageInfo::MakeN32Premul(width, height), props);
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}
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#endif
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static SkSurface* NewRasterN32Premul(int width, int height, const SkSurfaceProps* props = NULL) {
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return NewRaster(SkImageInfo::MakeN32Premul(width, height), props);
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}
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/**
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* Return a new surface using the specified render target.
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*/
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static SkSurface* NewRenderTargetDirect(GrRenderTarget*, const SkSurfaceProps*);
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static SkSurface* NewRenderTargetDirect(GrRenderTarget* target) {
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return NewRenderTargetDirect(target, NULL);
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}
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/**
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* Return a new surface whose contents will be drawn to an offscreen
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* render target, allocated by the surface.
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*/
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static SkSurface* NewRenderTarget(GrContext*, const SkImageInfo&, int sampleCount,
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const SkSurfaceProps* = NULL);
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static SkSurface* NewRenderTarget(GrContext* gr, const SkImageInfo& info) {
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return NewRenderTarget(gr, info, 0, NULL);
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}
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/**
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* Return a new surface whose contents will be drawn to an offscreen
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* render target, allocated by the surface from the scratch texture pool
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* managed by the GrContext. The scratch texture pool serves the purpose
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* of retaining textures after they are no longer in use in order to
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* re-use them later without having to re-allocate. Scratch textures
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* should be used in cases where high turnover is expected. This allows,
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* for example, the copy on write to recycle a texture from a recently
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* released SkImage snapshot of the surface.
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* Note: Scratch textures count against the GrContext's cached resource
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* budget.
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*/
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static SkSurface* NewScratchRenderTarget(GrContext*, const SkImageInfo&, int sampleCount,
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const SkSurfaceProps* = NULL);
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static SkSurface* NewScratchRenderTarget(GrContext* gr, const SkImageInfo& info) {
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return NewScratchRenderTarget(gr, info, 0, NULL);
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}
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int width() const { return fWidth; }
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int height() const { return fHeight; }
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/**
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* Returns a unique non-zero, unique value identifying the content of this
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* surface. Each time the content is changed changed, either by drawing
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* into this surface, or explicitly calling notifyContentChanged()) this
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* method will return a new value.
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*
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* If this surface is empty (i.e. has a zero-dimention), this will return
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* 0.
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*/
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uint32_t generationID();
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/**
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* Modes that can be passed to notifyContentWillChange
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*/
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enum ContentChangeMode {
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/**
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* Use this mode if it is known that the upcoming content changes will
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* clear or overwrite prior contents, thus making them discardable.
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*/
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kDiscard_ContentChangeMode,
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/**
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* Use this mode if prior surface contents need to be preserved or
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* if in doubt.
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*/
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kRetain_ContentChangeMode,
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};
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/**
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* Call this if the contents are about to change. This will (lazily) force a new
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* value to be returned from generationID() when it is called next.
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*/
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void notifyContentWillChange(ContentChangeMode mode);
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/**
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* Return a canvas that will draw into this surface. This will always
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* return the same canvas for a given surface, and is manged/owned by the
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* surface. It should not be used when its parent surface has gone out of
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* scope.
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*/
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SkCanvas* getCanvas();
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/**
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* Return a new surface that is "compatible" with this one, in that it will
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* efficiently be able to be drawn into this surface. Typical calling
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* pattern:
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*
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* SkSurface* A = SkSurface::New...();
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* SkCanvas* canvasA = surfaceA->newCanvas();
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* ...
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* SkSurface* surfaceB = surfaceA->newSurface(...);
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* SkCanvas* canvasB = surfaceB->newCanvas();
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* ... // draw using canvasB
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* canvasA->drawSurface(surfaceB); // <--- this will always be optimal!
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*/
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SkSurface* newSurface(const SkImageInfo&);
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/**
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* Returns an image of the current state of the surface pixels up to this
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* point. Subsequent changes to the surface (by drawing into its canvas)
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* will not be reflected in this image.
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*/
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SkImage* newImageSnapshot();
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/**
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* Thought the caller could get a snapshot image explicitly, and draw that,
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* it seems that directly drawing a surface into another canvas might be
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* a common pattern, and that we could possibly be more efficient, since
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* we'd know that the "snapshot" need only live until we've handed it off
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* to the canvas.
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*/
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void draw(SkCanvas*, SkScalar x, SkScalar y, const SkPaint*);
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/**
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* If the surface has direct access to its pixels (i.e. they are in local
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* RAM) return the const-address of those pixels, and if not null, return
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* the ImageInfo and rowBytes. The returned address is only valid while
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* the surface object is in scope, and no API call is made on the surface
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* or its canvas.
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*
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* On failure, returns NULL and the info and rowBytes parameters are
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* ignored.
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*/
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const void* peekPixels(SkImageInfo* info, size_t* rowBytes);
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/**
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* Copy the pixels from the surface into the specified buffer (pixels + rowBytes),
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* converting them into the requested format (dstInfo). The surface pixels are read
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* starting at the specified (srcX,srcY) location.
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*
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* The specified ImageInfo and (srcX,srcY) offset specifies a source rectangle
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*
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* srcR.setXYWH(srcX, srcY, dstInfo.width(), dstInfo.height());
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*
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* srcR is intersected with the bounds of the base-layer. If this intersection is not empty,
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* then we have two sets of pixels (of equal size). Replace the dst pixels with the
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* corresponding src pixels, performing any colortype/alphatype transformations needed
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* (in the case where the src and dst have different colortypes or alphatypes).
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*
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* This call can fail, returning false, for several reasons:
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* - If srcR does not intersect the surface bounds.
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* - If the requested colortype/alphatype cannot be converted from the surface's types.
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*/
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bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes,
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int srcX, int srcY);
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const SkSurfaceProps& props() const { return fProps; }
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protected:
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SkSurface(int width, int height, const SkSurfaceProps*);
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SkSurface(const SkImageInfo&, const SkSurfaceProps*);
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// called by subclass if their contents have changed
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void dirtyGenerationID() {
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fGenerationID = 0;
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}
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private:
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const SkSurfaceProps fProps;
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const int fWidth;
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const int fHeight;
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uint32_t fGenerationID;
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typedef SkRefCnt INHERITED;
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};
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#endif
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