skia2/docs/examples/GradientShader_MakeLinear.cpp
Kevin Lubick 6f60a859c6 Fix matrix scoping issue in sample
Change-Id: Id0023a12a21957ec9236d4ffaa03134995388d60
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/278456
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
2020-03-23 13:44:53 +00:00

49 lines
1.7 KiB
C++

// Copyright 2020 Google LLC.
// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
#include "tools/fiddle/examples.h"
REG_FIDDLE(GradientShader_MakeLinear, 201, 201, false, 0) {
void draw(SkCanvas* canvas) {
// This fiddle draws 4 instances of a LinearGradient, demonstrating
// how the local matrix affects the gradient as well as the flag
// which controls unpremul vs premul color interpolation.
SkPaint strokePaint;
strokePaint.setStyle(SkPaint::kStroke_Style);
strokePaint.setColor(SK_ColorBLACK);
SkPaint p;
p.setStyle(SkPaint::kFill_Style);
SkColor transparentGreen = SkColorSetARGB(0, 0, 255, 255);
SkColor colors[] = { transparentGreen, SK_ColorBLUE, SK_ColorRED };
SkScalar positions[] = { 0.0, 0.65, 1.0 };
for (int i = 0; i < 4; i++) {
SkScalar blockX = (i % 2) * 100;
SkScalar blockY = (i / 2) * 100;
SkPoint pts[] = { {blockX, blockY}, {blockX + 50, blockY + 100} };
int flags = 0; // interpolate colors in unpremul
if (i % 2 == 1) {
// right column will have premul
flags = SkGradientShader::Flags::kInterpolateColorsInPremul_Flag;
}
SkMatrix matr = SkMatrix::I();
if (i / 2 == 1) {
// bottom row will be rotated 45 degrees.
matr.setRotate(45, blockX, blockY);
}
auto lgs = SkGradientShader::MakeLinear(
pts, colors, positions, 3, SkTileMode::kMirror,
flags, &matr);
p.setShader(lgs);
auto r = SkRect::MakeLTRB(blockX, blockY, blockX + 100, blockY + 100);
canvas->drawRect(r, p);
canvas->drawRect(r, strokePaint);
}
}
} // END FIDDLE