aosp12/external/skia/samplecode/SampleThinAA.cpp

551 lines
21 KiB
C++

/*
* Copyright 2019 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "samplecode/Sample.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkColorFilter.h"
#include "include/core/SkFont.h"
#include "include/core/SkImage.h"
#include "include/core/SkPath.h"
#include "include/core/SkSurface.h"
namespace skiagm {
class ShapeRenderer : public SkRefCntBase {
public:
static constexpr SkScalar kTileWidth = 20.f;
static constexpr SkScalar kTileHeight = 20.f;
// Draw the shape, limited to kTileWidth x kTileHeight. It must apply the local subpixel (tx,
// ty) translation and rotation by angle. Prior to these transform adjustments, the SkCanvas
// will only have pixel aligned translations (these are separated to make super-sampling
// renderers easier).
virtual void draw(SkCanvas* canvas, SkPaint* paint,
SkScalar tx, SkScalar ty, SkScalar angle) = 0;
virtual SkString name() = 0;
virtual sk_sp<ShapeRenderer> toHairline() = 0;
void applyLocalTransform(SkCanvas* canvas, SkScalar tx, SkScalar ty, SkScalar angle) {
canvas->translate(tx, ty);
canvas->rotate(angle, kTileWidth / 2.f, kTileHeight / 2.f);
}
};
class RectRenderer : public ShapeRenderer {
public:
static sk_sp<ShapeRenderer> Make() {
return sk_sp<ShapeRenderer>(new RectRenderer());
}
SkString name() override { return SkString("rect"); }
sk_sp<ShapeRenderer> toHairline() override {
// Not really available but can't return nullptr
return Make();
}
void draw(SkCanvas* canvas, SkPaint* paint, SkScalar tx, SkScalar ty, SkScalar angle) override {
SkScalar width = paint->getStrokeWidth();
paint->setStyle(SkPaint::kFill_Style);
this->applyLocalTransform(canvas, tx, ty, angle);
canvas->drawRect(SkRect::MakeLTRB(kTileWidth / 2.f - width / 2.f, 2.f,
kTileWidth / 2.f + width / 2.f, kTileHeight - 2.f),
*paint);
}
private:
RectRenderer() {}
using INHERITED = ShapeRenderer;
};
class PathRenderer : public ShapeRenderer {
public:
static sk_sp<ShapeRenderer> MakeLine(bool hairline = false) {
return MakeCurve(0.f, hairline);
}
static sk_sp<ShapeRenderer> MakeLines(SkScalar depth, bool hairline = false) {
return MakeCurve(-depth, hairline);
}
static sk_sp<ShapeRenderer> MakeCurve(SkScalar depth, bool hairline = false) {
return sk_sp<ShapeRenderer>(new PathRenderer(depth, hairline));
}
SkString name() override {
SkString name;
if (fHairline) {
name.append("hairline");
if (fDepth > 0.f) {
name.appendf("-curve-%.2f", fDepth);
}
} else if (fDepth > 0.f) {
name.appendf("curve-%.2f", fDepth);
} else if (fDepth < 0.f) {
name.appendf("line-%.2f", -fDepth);
} else {
name.append("line");
}
return name;
}
sk_sp<ShapeRenderer> toHairline() override {
return sk_sp<ShapeRenderer>(new PathRenderer(fDepth, true));
}
void draw(SkCanvas* canvas, SkPaint* paint, SkScalar tx, SkScalar ty, SkScalar angle) override {
SkPath path;
path.moveTo(kTileWidth / 2.f, 2.f);
if (fDepth > 0.f) {
path.quadTo(kTileWidth / 2.f + fDepth, kTileHeight / 2.f,
kTileWidth / 2.f, kTileHeight - 2.f);
} else {
if (fDepth < 0.f) {
path.lineTo(kTileWidth / 2.f + fDepth, kTileHeight / 2.f);
}
path.lineTo(kTileWidth / 2.f, kTileHeight - 2.f);
}
if (fHairline) {
// Fake thinner hairlines by making it transparent, conflating coverage and alpha
SkColor4f color = paint->getColor4f();
SkScalar width = paint->getStrokeWidth();
if (width > 1.f) {
// Can't emulate width larger than a pixel
return;
}
paint->setColor4f({color.fR, color.fG, color.fB, width}, nullptr);
paint->setStrokeWidth(0.f);
}
// Adding round caps forces Ganesh to use the path renderer for lines instead of converting
// them to rectangles (which are already explicitly tested). However, when not curved, the
// GrStyledShape will still find a way to turn it into a rrect draw so it doesn't hit the
// path renderer in that condition.
paint->setStrokeCap(SkPaint::kRound_Cap);
paint->setStrokeJoin(SkPaint::kMiter_Join);
paint->setStyle(SkPaint::kStroke_Style);
this->applyLocalTransform(canvas, tx, ty, angle);
canvas->drawPath(path, *paint);
}
private:
SkScalar fDepth; // 0.f to make a line, otherwise outset of curve from end points
bool fHairline;
PathRenderer(SkScalar depth, bool hairline)
: fDepth(depth)
, fHairline(hairline) {}
using INHERITED = ShapeRenderer;
};
class OffscreenShapeRenderer : public ShapeRenderer {
public:
~OffscreenShapeRenderer() override = default;
static sk_sp<OffscreenShapeRenderer> Make(sk_sp<ShapeRenderer> renderer, int supersample,
bool forceRaster = false) {
SkASSERT(supersample > 0);
return sk_sp<OffscreenShapeRenderer>(new OffscreenShapeRenderer(std::move(renderer),
supersample, forceRaster));
}
SkString name() override {
SkString name = fRenderer->name();
if (fSupersampleFactor != 1) {
name.prependf("%dx-", fSupersampleFactor * fSupersampleFactor);
}
return name;
}
sk_sp<ShapeRenderer> toHairline() override {
return Make(fRenderer->toHairline(), fSupersampleFactor, fForceRasterBackend);
}
void draw(SkCanvas* canvas, SkPaint* paint, SkScalar tx, SkScalar ty, SkScalar angle) override {
// Subpixel translation+angle are applied in the offscreen buffer
this->prepareBuffer(canvas, paint, tx, ty, angle);
this->redraw(canvas);
}
// Exposed so that it's easy to fill the offscreen buffer, then draw zooms/filters of it before
// drawing the original scale back into the canvas.
void prepareBuffer(SkCanvas* canvas, SkPaint* paint, SkScalar tx, SkScalar ty, SkScalar angle) {
auto info = SkImageInfo::Make(fSupersampleFactor * kTileWidth,
fSupersampleFactor * kTileHeight,
kRGBA_8888_SkColorType, kPremul_SkAlphaType);
auto surface = fForceRasterBackend ? SkSurface::MakeRaster(info)
: canvas->makeSurface(info);
surface->getCanvas()->save();
// Make fully transparent so it is easy to determine pixels that are touched by partial cov.
surface->getCanvas()->clear(SK_ColorTRANSPARENT);
// Set up scaling to fit supersampling amount
surface->getCanvas()->scale(fSupersampleFactor, fSupersampleFactor);
fRenderer->draw(surface->getCanvas(), paint, tx, ty, angle);
surface->getCanvas()->restore();
// Save image so it can be drawn zoomed in or to visualize touched pixels; only valid until
// the next call to draw()
fLastRendered = surface->makeImageSnapshot();
}
void redraw(SkCanvas* canvas, SkScalar scale = 1.f, bool debugMode = false) {
SkASSERT(fLastRendered);
// Use medium quality filter to get mipmaps when drawing smaller, or use nearest filtering
// when upscaling
SkPaint blit;
if (debugMode) {
// Makes anything that's > 1/255 alpha fully opaque and sets color to medium green.
static constexpr float kFilter[] = {
0.f, 0.f, 0.f, 0.f, 16.f/255,
0.f, 0.f, 0.f, 0.f, 200.f/255,
0.f, 0.f, 0.f, 0.f, 16.f/255,
0.f, 0.f, 0.f, 255.f, 0.f
};
blit.setColorFilter(SkColorFilters::Matrix(kFilter));
}
canvas->scale(scale, scale);
canvas->drawImageRect(fLastRendered.get(),
SkRect::MakeWH(kTileWidth, kTileHeight),
SkRect::MakeWH(kTileWidth, kTileHeight),
SkSamplingOptions(scale > 1.f ? kNone_SkFilterQuality
: kMedium_SkFilterQuality),
&blit,
SkCanvas::kFast_SrcRectConstraint);
}
private:
bool fForceRasterBackend;
sk_sp<SkImage> fLastRendered;
sk_sp<ShapeRenderer> fRenderer;
int fSupersampleFactor;
OffscreenShapeRenderer(sk_sp<ShapeRenderer> renderer, int supersample, bool forceRaster)
: fForceRasterBackend(forceRaster)
, fLastRendered(nullptr)
, fRenderer(std::move(renderer))
, fSupersampleFactor(supersample) { }
using INHERITED = ShapeRenderer;
};
class ThinAASample : public Sample {
public:
ThinAASample() {
this->setBGColor(0xFFFFFFFF);
}
protected:
void onOnceBeforeDraw() override {
// Setup all base renderers
fShapes.push_back(RectRenderer::Make());
fShapes.push_back(PathRenderer::MakeLine());
fShapes.push_back(PathRenderer::MakeLines(4.f)); // 2 segments
fShapes.push_back(PathRenderer::MakeCurve(2.f)); // Shallow curve
fShapes.push_back(PathRenderer::MakeCurve(8.f)); // Deep curve
for (int i = 0; i < fShapes.count(); ++i) {
fNative.push_back(OffscreenShapeRenderer::Make(fShapes[i], 1));
fRaster.push_back(OffscreenShapeRenderer::Make(fShapes[i], 1, /* raster */ true));
fSS4.push_back(OffscreenShapeRenderer::Make(fShapes[i], 4)); // 4x4 -> 16 samples
fSS16.push_back(OffscreenShapeRenderer::Make(fShapes[i], 8)); // 8x8 -> 64 samples
fHairline.push_back(OffscreenShapeRenderer::Make(fRaster[i]->toHairline(), 1));
}
// Start it at something subpixel
fStrokeWidth = 0.5f;
fSubpixelX = 0.f;
fSubpixelY = 0.f;
fAngle = 0.f;
fCurrentStage = AnimStage::kMoveLeft;
fLastFrameTime = -1.f;
// Don't animate in the beginning
fAnimTranslate = false;
fAnimRotate = false;
}
void onDrawContent(SkCanvas* canvas) override {
// Move away from screen edge and add instructions
SkPaint text;
SkFont font(nullptr, 12);
canvas->translate(60.f, 20.f);
canvas->drawString("Each row features a rendering command under different AA strategies. "
"Native refers to the current backend of the viewer, e.g. OpenGL.",
0, 0, font, text);
canvas->drawString(SkStringPrintf("Stroke width: %.2f ('-' to decrease, '=' to increase)",
fStrokeWidth), 0, 24, font, text);
canvas->drawString(SkStringPrintf("Rotation: %.3f ('r' to animate, 'y' sets to 90, 'u' sets"
" to 0, 'space' adds 15)", fAngle), 0, 36, font, text);
canvas->drawString(SkStringPrintf("Translation: %.3f, %.3f ('t' to animate)",
fSubpixelX, fSubpixelY), 0, 48, font, text);
canvas->translate(0.f, 100.f);
// Draw with surface matching current viewer surface type
this->drawShapes(canvas, "Native", 0, fNative);
// Draw with forced raster backend so it's easy to compare side-by-side
this->drawShapes(canvas, "Raster", 1, fRaster);
// Draw paths as hairlines + alpha hack
this->drawShapes(canvas, "Hairline", 2, fHairline);
// Draw at 4x supersampling in bottom left
this->drawShapes(canvas, "SSx16", 3, fSS4);
// And lastly 16x supersampling in bottom right
this->drawShapes(canvas, "SSx64", 4, fSS16);
}
bool onAnimate(double nanos) override {
SkScalar t = 1e-9 * nanos;
SkScalar dt = fLastFrameTime < 0.f ? 0.f : t - fLastFrameTime;
fLastFrameTime = t;
if (!fAnimRotate && !fAnimTranslate) {
// Keep returning true so that the last frame time is tracked
fLastFrameTime = -1.f;
return false;
}
switch(fCurrentStage) {
case AnimStage::kMoveLeft:
fSubpixelX += 2.f * dt;
if (fSubpixelX >= 1.f) {
fSubpixelX = 1.f;
fCurrentStage = AnimStage::kMoveDown;
}
break;
case AnimStage::kMoveDown:
fSubpixelY += 2.f * dt;
if (fSubpixelY >= 1.f) {
fSubpixelY = 1.f;
fCurrentStage = AnimStage::kMoveRight;
}
break;
case AnimStage::kMoveRight:
fSubpixelX -= 2.f * dt;
if (fSubpixelX <= -1.f) {
fSubpixelX = -1.f;
fCurrentStage = AnimStage::kMoveUp;
}
break;
case AnimStage::kMoveUp:
fSubpixelY -= 2.f * dt;
if (fSubpixelY <= -1.f) {
fSubpixelY = -1.f;
fCurrentStage = fAnimRotate ? AnimStage::kRotate : AnimStage::kMoveLeft;
}
break;
case AnimStage::kRotate: {
SkScalar newAngle = fAngle + dt * 15.f;
bool completed = SkScalarMod(newAngle, 15.f) < SkScalarMod(fAngle, 15.f);
fAngle = SkScalarMod(newAngle, 360.f);
if (completed) {
// Make sure we're on a 15 degree boundary
fAngle = 15.f * SkScalarRoundToScalar(fAngle / 15.f);
if (fAnimTranslate) {
fCurrentStage = this->getTranslationStage();
}
}
} break;
}
return true;
}
SkString name() override { return SkString("Thin-AA"); }
bool onChar(SkUnichar key) override {
switch(key) {
case 't':
// Toggle translation animation.
fAnimTranslate = !fAnimTranslate;
if (!fAnimTranslate && fAnimRotate && fCurrentStage != AnimStage::kRotate) {
// Turned off an active translation so go to rotating
fCurrentStage = AnimStage::kRotate;
} else if (fAnimTranslate && !fAnimRotate &&
fCurrentStage == AnimStage::kRotate) {
// Turned on translation, rotation had been paused too, so reset the stage
fCurrentStage = this->getTranslationStage();
}
return true;
case 'r':
// Toggle rotation animation.
fAnimRotate = !fAnimRotate;
if (!fAnimRotate && fAnimTranslate && fCurrentStage == AnimStage::kRotate) {
// Turned off an active rotation so go back to translation
fCurrentStage = this->getTranslationStage();
} else if (fAnimRotate && !fAnimTranslate &&
fCurrentStage != AnimStage::kRotate) {
// Turned on rotation, translation had been paused too, so reset to rotate
fCurrentStage = AnimStage::kRotate;
}
return true;
case 'u': fAngle = 0.f; return true;
case 'y': fAngle = 90.f; return true;
case ' ': fAngle = SkScalarMod(fAngle + 15.f, 360.f); return true;
case '-': fStrokeWidth = std::max(0.1f, fStrokeWidth - 0.05f); return true;
case '=': fStrokeWidth = std::min(1.f, fStrokeWidth + 0.05f); return true;
}
return false;
}
private:
// Base renderers that get wrapped on the offscreen renderers so that they can be transformed
// for visualization, or supersampled.
SkTArray<sk_sp<ShapeRenderer>> fShapes;
SkTArray<sk_sp<OffscreenShapeRenderer>> fNative;
SkTArray<sk_sp<OffscreenShapeRenderer>> fRaster;
SkTArray<sk_sp<OffscreenShapeRenderer>> fHairline;
SkTArray<sk_sp<OffscreenShapeRenderer>> fSS4;
SkTArray<sk_sp<OffscreenShapeRenderer>> fSS16;
SkScalar fStrokeWidth;
// Animated properties to stress the AA algorithms
enum class AnimStage {
kMoveRight, kMoveDown, kMoveLeft, kMoveUp, kRotate
} fCurrentStage;
SkScalar fLastFrameTime;
bool fAnimRotate;
bool fAnimTranslate;
// Current frame's animation state
SkScalar fSubpixelX;
SkScalar fSubpixelY;
SkScalar fAngle;
AnimStage getTranslationStage() {
// For paused translations (i.e. fAnimTranslate toggled while translating), the current
// stage moves to kRotate, but when restarting the translation animation, we want to
// go back to where we were without losing any progress.
if (fSubpixelX > -1.f) {
if (fSubpixelX >= 1.f) {
// Can only be moving down on right edge, given our transition states
return AnimStage::kMoveDown;
} else if (fSubpixelY > 0.f) {
// Can only be moving right along top edge
return AnimStage::kMoveRight;
} else {
// Must be moving left along bottom edge
return AnimStage::kMoveLeft;
}
} else {
// Moving up along the left edge, or is at the very top so start moving left
return fSubpixelY > -1.f ? AnimStage::kMoveUp : AnimStage::kMoveLeft;
}
}
void drawShapes(SkCanvas* canvas, const char* name, int gridX,
SkTArray<sk_sp<OffscreenShapeRenderer>> shapes) {
SkAutoCanvasRestore autoRestore(canvas, /* save */ true);
for (int i = 0; i < shapes.count(); ++i) {
this->drawShape(canvas, name, gridX, shapes[i].get(), i == 0);
// drawShape positions the canvas properly for the next iteration
}
}
void drawShape(SkCanvas* canvas, const char* name, int gridX,
OffscreenShapeRenderer* shape, bool drawNameLabels) {
static constexpr SkScalar kZoomGridWidth = 8 * ShapeRenderer::kTileWidth + 8.f;
static constexpr SkRect kTile = SkRect::MakeWH(ShapeRenderer::kTileWidth,
ShapeRenderer::kTileHeight);
static constexpr SkRect kZoomTile = SkRect::MakeWH(8 * ShapeRenderer::kTileWidth,
8 * ShapeRenderer::kTileHeight);
// Labeling per shape and detailed labeling that isn't per-stroke
canvas->save();
SkPaint text;
SkFont font(nullptr, 12);
if (gridX == 0) {
SkString name = shape->name();
SkScalar centering = name.size() * 4.f; // ad-hoc
canvas->save();
canvas->translate(-10.f, 4 * ShapeRenderer::kTileHeight + centering);
canvas->rotate(-90.f);
canvas->drawString(shape->name(), 0.f, 0.f, font, text);
canvas->restore();
}
if (drawNameLabels) {
canvas->drawString(name, gridX * kZoomGridWidth, -10.f, font, text);
}
canvas->restore();
// Paints for outlines and actual shapes
SkPaint outline;
outline.setStyle(SkPaint::kStroke_Style);
SkPaint clear;
clear.setColor(SK_ColorWHITE);
SkPaint paint;
paint.setAntiAlias(true);
paint.setStrokeWidth(fStrokeWidth);
// Generate a saved image of the correct stroke width, but don't put it into the canvas
// yet since we want to draw the "original" size on top of the zoomed in version
shape->prepareBuffer(canvas, &paint, fSubpixelX, fSubpixelY, fAngle);
// Draw it at 8X zoom
SkScalar x = gridX * kZoomGridWidth;
canvas->save();
canvas->translate(x, 0.f);
canvas->drawRect(kZoomTile, outline);
shape->redraw(canvas, 8.0f);
canvas->restore();
// Draw the original
canvas->save();
canvas->translate(x + 4.f, 4.f);
canvas->drawRect(kTile, clear);
canvas->drawRect(kTile, outline);
shape->redraw(canvas, 1.f);
canvas->restore();
// Now redraw it into the coverage location (just to the right of the original scale)
canvas->save();
canvas->translate(x + ShapeRenderer::kTileWidth + 8.f, 4.f);
canvas->drawRect(kTile, clear);
canvas->drawRect(kTile, outline);
shape->redraw(canvas, 1.f, /* debug */ true);
canvas->restore();
// Lastly, shift the canvas translation down by 8 * kTH + padding for the next set of shapes
canvas->translate(0.f, 8.f * ShapeRenderer::kTileHeight + 20.f);
}
using INHERITED = Sample;
};
//////////////////////////////////////////////////////////////////////////////
DEF_SAMPLE( return new ThinAASample; )
} // namespace skiagm