Centralize decision about whether to do bicubic filtering, and fallbacks to mip, bilerp, or nearest
R=robertphillips@google.com, humper@google.com
Author: bsalomon@google.com
Review URL: https://codereview.chromium.org/282293004
git-svn-id: http://skia.googlecode.com/svn/trunk@14809 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/effects/GrBicubicEffect.cpp b/src/gpu/effects/GrBicubicEffect.cpp
index 89124ff..9c6d1a3 100644
--- a/src/gpu/effects/GrBicubicEffect.cpp
+++ b/src/gpu/effects/GrBicubicEffect.cpp
@@ -177,3 +177,36 @@
}
return GrBicubicEffect::Create(textures[texIdx], coefficients);
}
+
+//////////////////////////////////////////////////////////////////////////////
+
+bool GrBicubicEffect::ShouldUseBicubic(const SkMatrix& matrix,
+ GrTextureParams::FilterMode* filterMode) {
+ if (matrix.isIdentity()) {
+ *filterMode = GrTextureParams::kNone_FilterMode;
+ return false;
+ }
+
+ SkScalar scales[2];
+ if (!matrix.getMinMaxScales(scales) || scales[0] < SK_Scalar1) {
+ // Bicubic doesn't handle arbitrary minimization well, as src texels can be skipped
+ // entirely,
+ *filterMode = GrTextureParams::kMipMap_FilterMode;
+ return false;
+ }
+ // At this point if scales[1] == SK_Scalar1 then the matrix doesn't do any scaling.
+ if (scales[1] == SK_Scalar1) {
+ if (matrix.rectStaysRect() && SkScalarIsInt(matrix.getTranslateX()) &&
+ SkScalarIsInt(matrix.getTranslateY())) {
+ *filterMode = GrTextureParams::kNone_FilterMode;
+ } else {
+ // Use bilerp to handle rotation or fractional translation.
+ *filterMode = GrTextureParams::kBilerp_FilterMode;
+ }
+ return false;
+ }
+ // When we use the bicubic filtering effect each sample is read from the texture using
+ // nearest neighbor sampling.
+ *filterMode = GrTextureParams::kNone_FilterMode;
+ return true;
+}