backdrop.cpp File Reference

#include "gm/gm.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkColor.h"
#include "include/core/SkImageFilter.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPictureRecorder.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkScalar.h"
#include "include/core/SkShader.h"
#include "include/core/SkTypes.h"
#include "include/effects/SkGradientShader.h"
#include "include/effects/SkImageFilters.h"
#include "src/core/SkCanvasPriv.h"
#include "src/core/SkMatrixPriv.h"
#include <initializer_list>

Go to the source code of this file.

Functions
static sk_sp< SkShader >	make_shader (SkScalar cx, SkScalar cy, SkScalar rad)
static void	do_draw (SkCanvas *canvas, bool useClip, bool useHintRect, SkScalar scaleFactor)
	DEF_SIMPLE_GM (backdrop_hintrect_clipping, canvas, 512, 1024)
	DEF_SIMPLE_GM (backdrop_scalefactor, canvas, 768, 1024)

Function Documentation

DEF_SIMPLE_GM() [1/2]

DEF_SIMPLE_GM	(	backdrop_hintrect_clipping	,
		canvas	,
		512	,
		1024
	)

Definition at line 88 of file backdrop.cpp.

                                                             {
    for (bool useHintRect : {false, true}) {
        for (bool useClip : {false, true}) {
            canvas->save();
                do_draw(canvas, useClip, useHintRect, 1.0f);
 
                SkPictureRecorder rec;
                do_draw(rec.beginRecording(256, 256), useClip, useHintRect, 1.0f);
                canvas->translate(256, 0);
                canvas->drawPicture(rec.finishRecordingAsPicture());
            canvas->restore();
 
            canvas->translate(0, 256);
        }
    }
}

DEF_SIMPLE_GM() [2/2]

DEF_SIMPLE_GM	(	backdrop_scalefactor	,
		canvas	,
		768	,
		1024
	)

Definition at line 113 of file backdrop.cpp.

                                                       {
    for (bool useHintRect : {false, true}) {
        for (bool useClip : {false, true}) {
            canvas->save();
                do_draw(canvas, useClip, useHintRect, 1.0f);
                canvas->translate(256, 0);
                do_draw(canvas, useClip, useHintRect, 0.25f);
                canvas->translate(256, 0);
                do_draw(canvas, useClip, useHintRect, 0.1f);
            canvas->restore();
 
            canvas->translate(0, 256);
        }
    }
}

do_draw()

static void do_draw ( SkCanvas *  canvas, bool  useClip, bool  useHintRect, SkScalar  scaleFactor  )

static

Definition at line 41 of file backdrop.cpp.

                                                                                            {
    SkAutoCanvasRestore acr(canvas, true);
    canvas->clipRect({0, 0, 256, 256});
 
    const SkScalar cx = 128, cy = 128, rad = 100;
    SkPaint p;
    p.setShader(make_shader(cx, cy, rad));
    p.setAntiAlias(true);
    canvas->drawCircle(cx, cy, rad, p);
 
    // now setup a saveLayer that will pull in the backdrop and blur it
    //
    const SkRect r = {cx-50, cy-50, cx+50, cy+50};
    const SkRect* drawrptr = useHintRect ? &r : nullptr;
    const SkScalar sigma = 10;
    if (useClip) {
        canvas->clipRect(r);
    }
    // Using kClamp because kDecal, the default, produces transparency near the edge of the canvas's
    // device.
    SkRect blurCrop;
    SkAssertResult(SkMatrixPriv::InverseMapRect(canvas->getLocalToDeviceAs3x3(),
                                                &blurCrop,
                                                SkRect::MakeWH(canvas->imageInfo().width(),
                                                               canvas->imageInfo().height())));
    auto blur = SkImageFilters::Blur(sigma, sigma, SkTileMode::kClamp, nullptr, blurCrop);
    auto rec = SkCanvasPriv::ScaledBackdropLayer(drawrptr, nullptr, blur.get(), scaleFactor, 0);
    canvas->saveLayer(rec);
        // draw something inside, just to demonstrate that we don't blur the new contents,
        // just the backdrop.
        p.setColor(SK_ColorYELLOW);
        p.setShader(nullptr);
        canvas->drawCircle(cx, cy, 30, p);
    canvas->restore();
}

make_shader()

static sk_sp< SkShader > make_shader ( SkScalar  cx, SkScalar  cy, SkScalar  rad  )

static

Definition at line 28 of file backdrop.cpp.

                                                                           {
    const SkColor colors[] = {
        SK_ColorRED, SK_ColorRED, SK_ColorBLUE, SK_ColorBLUE, SK_ColorGREEN, SK_ColorGREEN,
        SK_ColorRED, SK_ColorRED, SK_ColorBLUE, SK_ColorBLUE, SK_ColorGREEN, SK_ColorGREEN,
    };
    constexpr int count = std::size(colors);
    SkScalar pos[count] = { 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6 };
    for (int i = 0; i < count; ++i) {
        pos[i] *= 1.0f/6;
    }
    return SkGradientShader::MakeSweep(cx, cy, colors, pos, count);
}