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Bug 1719215 - Constrain clipping in CreateSubImageForData(). r=lsalzman

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Differential Revision: https://phabricator.services.mozilla.com/D137777
This commit is contained in:
Steven Michaud 2022-02-03 18:54:01 +00:00
parent 36c0803568
commit 4c3344cc89
1 changed files with 11 additions and 2 deletions
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13
gfx/2d/DrawTargetCairo.cpp
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@ -254,6 +254,15 @@ static cairo_surface_t* GetAsImageSurface(cairo_surface_t* aSurface) {
return nullptr;
}
// We're creating a subimage from the parent image's data (in aData) without
// altering that data or its stride. This constrains the values in aRect, and
// how they're used. Callers must see to it that the parent fully contains the
// subimage. Here we ensure that no clipping is done in the X dimension at the
// beginning of any line. (To do otherwise would require creating a copy of
// aData from parts of every line in aData (from aRect.Y() to aRect.Height()),
// and setting the copy to a different stride.) A non-zero aRect.X() is used
// only to specify the subimage's location in its parent (via
// cairo_surface_set_device_offset()). This change resolves bug 1719215.
static cairo_surface_t* CreateSubImageForData(unsigned char* aData,
const IntRect& aRect, int aStride,
SurfaceFormat aFormat) {
@ -261,12 +270,12 @@ static cairo_surface_t* CreateSubImageForData(unsigned char* aData,
gfxWarning() << "DrawTargetCairo.CreateSubImageForData null aData";
return nullptr;
}
unsigned char* data =
aData + aRect.Y() * aStride + aRect.X() * BytesPerPixel(aFormat);
unsigned char* data = aData + aRect.Y() * aStride;
cairo_surface_t* image = cairo_image_surface_create_for_data(
data, GfxFormatToCairoFormat(aFormat), aRect.Width(), aRect.Height(),
aStride);
// Set the subimage's location in its parent
cairo_surface_set_device_offset(image, -aRect.X(), -aRect.Y());
return image;
}