avoid deep copies of pixels with Skia raster surfaces (tdf#132856)

SkCanvas::draw() leads to deep copies of the source bitmap, moreover
RasterWindowContext_win allocates the pixels in a way that
SkSurface_Raster has to do a deep copy because of not owning
the pixels.

Change-Id: I22f6a2c0f96faf99f94140eff26ec0c22fae96d9
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/93958
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

2 files changed, 40 insertions, 0 deletions

diff --git a/external/skia/UnpackedTarball_skia.mk b/external/skia/UnpackedTarball_skia.mk
index e0841e432daa..08769b2867a5 100644
--- a/external/skia/UnpackedTarball_skia.mk
+++ b/external/skia/UnpackedTarball_skia.mk
@@ -34,6 +34,7 @@ skia_patches := \
     fix-without-gl.patch.0 \
     extend-rgb-to-rgba.patch.0 \
     windows-typeface-directwrite.patch.0 \
+    windows-raster-surface-no-copies.patch.1 \
 
 $(eval $(call gb_UnpackedTarball_set_patchlevel,skia,1))
 
diff --git a/external/skia/windows-raster-surface-no-copies.patch.1 b/external/skia/windows-raster-surface-no-copies.patch.1
new file mode 100644
index 000000000000..0c5804d8558b
--- /dev/null
+++ b/external/skia/windows-raster-surface-no-copies.patch.1
@@ -0,0 +1,39 @@
+diff --git a/tools/sk_app/win/RasterWindowContext_win.cpp b/tools/sk_app/win/RasterWindowContext_win.cpp
+index 9548220ce6..49f1f9ed17 100644
+--- a/tools/sk_app/win/RasterWindowContext_win.cpp
++++ b/tools/sk_app/win/RasterWindowContext_win.cpp
+@@ -55,7 +55,7 @@ void RasterWindowContext_win::resize(int w, int h) {
+     fWidth = w;
+     fHeight = h;
+     fBackbufferSurface.reset();
+-    const size_t bmpSize = sizeof(BITMAPINFOHEADER) + w * h * sizeof(uint32_t);
++    const size_t bmpSize = sizeof(BITMAPINFO);
+     fSurfaceMemory.reset(bmpSize);
+     BITMAPINFO* bmpInfo = reinterpret_cast<BITMAPINFO*>(fSurfaceMemory.get());
+     ZeroMemory(bmpInfo, sizeof(BITMAPINFO));
+@@ -65,11 +65,12 @@ void RasterWindowContext_win::resize(int w, int h) {
+     bmpInfo->bmiHeader.biPlanes = 1;
+     bmpInfo->bmiHeader.biBitCount = 32;
+     bmpInfo->bmiHeader.biCompression = BI_RGB;
+-    void* pixels = bmpInfo->bmiColors;
++    // Do not use a packed DIB bitmap, SkSurface_Raster::onNewImageSnapshot() does
++    // a deep copy if it does not own the pixels.
+ 
+     SkImageInfo info = SkImageInfo::Make(w, h, fDisplayParams.fColorType, kPremul_SkAlphaType,
+                                          fDisplayParams.fColorSpace);
+-    fBackbufferSurface = SkSurface::MakeRasterDirect(info, pixels, sizeof(uint32_t) * w);
++    fBackbufferSurface = SkSurface::MakeRaster(info);
+ }
+ 
+ sk_sp<SkSurface> RasterWindowContext_win::getBackbufferSurface() { return fBackbufferSurface; }
+@@ -77,7 +78,9 @@ sk_sp<SkSurface> RasterWindowContext_win::getBackbufferSurface() { return fBackb
+ void RasterWindowContext_win::swapBuffers() {
+     BITMAPINFO* bmpInfo = reinterpret_cast<BITMAPINFO*>(fSurfaceMemory.get());
+     HDC dc = GetDC(fWnd);
+-    StretchDIBits(dc, 0, 0, fWidth, fHeight, 0, 0, fWidth, fHeight, bmpInfo->bmiColors, bmpInfo,
++    SkPixmap pixmap;
++    fBackbufferSurface->peekPixels(&pixmap);
++    StretchDIBits(dc, 0, 0, fWidth, fHeight, 0, 0, fWidth, fHeight, pixmap.addr(), bmpInfo,
+                   DIB_RGB_COLORS, SRCCOPY);
+     ReleaseDC(fWnd, dc);
+ }