skia2/docs/examples/mapradius.cpp
Hal Canary 6c8422c671 add more docs/examples from named fiddles.
ignore offscreen, srgb, and animated fiddles for now.

Change-Id: I923131b684865698e6cda138b004930e11f504d5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/263713
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
2020-01-14 19:22:26 +00:00

34 lines
1.6 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(mapradius, 256, 256, false, 0) {
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
SkMatrix matrix;
const SkPoint center = {128, 103};
matrix.setScale(2, .5f, center.fX, center.fY);
matrix.postRotate(45, center.fX, center.fY);
const SkScalar circleRadius = 60;
SkScalar mappedRadius = matrix.mapRadius(circleRadius);
SkVector minorAxis, majorAxis;
matrix.mapVector(0, circleRadius, &minorAxis);
matrix.mapVector(circleRadius, 0, &majorAxis);
paint.setColor(SK_ColorRED);
canvas->drawLine(40, 240, 40 + minorAxis.length(), 240, paint);
canvas->drawLine(42 + minorAxis.length(), 240, 42 + minorAxis.length() + majorAxis.length(),
240, paint);
paint.setColor(SK_ColorBLACK);
canvas->drawLine(center.fX, center.fY, center.fX + mappedRadius, center.fY, paint);
canvas->drawLine(center.fX, center.fY, center.fX, center.fY + mappedRadius, paint);
canvas->drawLine(40, 220, 40 + mappedRadius, 220, paint);
canvas->drawLine(42 + mappedRadius, 220, 42 + mappedRadius * 2, 220, paint);
canvas->concat(matrix);
canvas->drawCircle(center.fX, center.fY, circleRadius, paint);
paint.setColor(SK_ColorRED);
canvas->drawLine(center.fX, center.fY, center.fX + circleRadius, center.fY, paint);
canvas->drawLine(center.fX, center.fY, center.fX, center.fY + circleRadius, paint);
}
} // END FIDDLE