commit 30deee2265e76052c320a0c1f84486c6dd1bebc3
author Luboš Luňák <l.lunak@collabora.com> Fri Jun 12 16:03:40 2020 +0200
committer Luboš Luňák <l.lunak@collabora.com> Mon Jun 15 10:07:07 2020 +0200
tree 4ac43ad7c572b71dc0a0fa35a2433c2b5ee177d6
parent 104173946f1989bc7d7b36855a5058da8cc3409c

fix skewed drawing in Skia's drawTransformedBitmap() (tdf#133925)

In debug builds this led to an assert with the bugdoc, in optimized
builds it seems to cause drawing problems.

Change-Id: Id52309f2e3d33f8b68952d988b927cea7546d131
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/96206
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

vcl/skia/gdiimpl.cxx

diff --git a/vcl/skia/gdiimpl.cxx b/vcl/skia/gdiimpl.cxx
index 58d59cf..7e52230 100644
--- a/vcl/skia/gdiimpl.cxx
+++ b/vcl/skia/gdiimpl.cxx
@@ -1380,8 +1380,8 @@
    // using the rNull, rX, rY points as destinations for the (0,0), (Width,0), (0,Height) source points.
    // Round to pixels, otherwise kMScaleX/Y below could be slightly != 1, causing unnecessary uncached
    // scaling.
    const basegfx::B2IVector aXRel = basegfx::fround(rX - rNull);
    const basegfx::B2IVector aYRel = basegfx::fround(rY - rNull);
    const basegfx::B2DVector aXRel = basegfx::B2DTuple(basegfx::fround(rX - rNull));
    const basegfx::B2DVector aYRel = basegfx::B2DTuple(basegfx::fround(rY - rNull));

    const Size aSize = rSourceBitmap.GetSize();

@@ -1389,18 +1389,15 @@
    SAL_INFO("vcl.skia.trace", "drawtransformedbitmap(" << this << "): " << aSize << " " << rNull
                                                        << ":" << rX << ":" << rY);

    // TODO: How to cache properly skewed images?
    bool blockCaching = (aXRel.getY() != 0 || aYRel.getX() != 0);
    const Size imageSize(aXRel.getX(), aYRel.getY());
    sk_sp<SkImage> imageToDraw
        = mergeBitmaps(rSkiaBitmap, pSkiaAlphaBitmap, imageSize, blockCaching);
    const Size imageSize(aXRel.getLength(), aXRel.getLength());
    sk_sp<SkImage> imageToDraw = mergeBitmaps(rSkiaBitmap, pSkiaAlphaBitmap, imageSize);
    if (!imageToDraw)
        return false;

    SkMatrix aMatrix;
    aMatrix.set(SkMatrix::kMScaleX, aXRel.getX() / imageToDraw->width());
    aMatrix.set(SkMatrix::kMSkewY, aXRel.getY() / aSize.Width());
    aMatrix.set(SkMatrix::kMSkewX, aYRel.getX() / aSize.Height());
    aMatrix.set(SkMatrix::kMSkewY, aXRel.getY() / imageToDraw->width());
    aMatrix.set(SkMatrix::kMSkewX, aYRel.getX() / imageToDraw->height());
    aMatrix.set(SkMatrix::kMScaleY, aYRel.getY() / imageToDraw->height());
    aMatrix.set(SkMatrix::kMTransX, rNull.getX());
    aMatrix.set(SkMatrix::kMTransY, rNull.getY());