94 lines
2.4 KiB
C++
94 lines
2.4 KiB
C++
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#include "SampleCode.h"
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#include "SkColorPriv.h"
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#include "SkGradientShader.h"
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#include "SkView.h"
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#include "SkCanvas.h"
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#include "SkUtils.h"
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static SkBitmap make_bitmap() {
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SkBitmap bm;
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SkColorTable* ctable = new SkColorTable(256);
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SkPMColor* c = ctable->lockColors();
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for (int i = 0; i < 256; i++) {
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c[i] = SkPackARGB32(255 - i, 0, 0, 0);
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}
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ctable->unlockColors(true);
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bm.setConfig(SkBitmap::kIndex8_Config, 256, 256);
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bm.allocPixels(ctable);
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ctable->unref();
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bm.lockPixels();
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const float cx = bm.width() * 0.5f;
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const float cy = bm.height() * 0.5f;
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for (int y = 0; y < bm.height(); y++) {
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float dy = y - cy;
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dy *= dy;
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uint8_t* p = bm.getAddr8(0, y);
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for (int x = 0; x < 256; x++) {
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float dx = x - cx;
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dx *= dx;
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float d = (dx + dy) / (cx/2);
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int id = (int)d;
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if (id > 255) {
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id = 255;
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}
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p[x] = id;
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}
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}
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bm.unlockPixels();
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return bm;
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}
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class ExtractAlphaView : public SkView {
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SkBitmap fBM8;
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SkBitmap fBM32;
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SkBitmap fBM4;
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public:
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ExtractAlphaView() {
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fBM8 = make_bitmap();
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fBM8.copyTo(&fBM32, SkBitmap::kARGB_8888_Config);
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fBM8.copyTo(&fBM4, SkBitmap::kARGB_4444_Config);
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}
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protected:
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// overrides from SkEventSink
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virtual bool onQuery(SkEvent* evt) {
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if (SampleCode::TitleQ(*evt)) {
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SampleCode::TitleR(evt, "DitherBitmap");
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return true;
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}
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return this->INHERITED::onQuery(evt);
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}
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void drawBG(SkCanvas* canvas) {
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canvas->drawColor(0xFFDDDDDD);
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}
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virtual void onDraw(SkCanvas* canvas) {
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drawBG(canvas);
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const SkBitmap* srcBM[] = { &fBM8, &fBM32, &fBM4 };
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SkPaint paint;
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paint.setColor(SK_ColorRED);
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for (int i = 0; i < 3; i++) {
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canvas->drawBitmap(*srcBM[i], 0, 0, &paint);
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SkBitmap tmp;
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srcBM[i]->extractAlpha(&tmp);
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canvas->drawBitmap(tmp, 0, SkIntToScalar(tmp.height() + 10), &paint);
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canvas->translate(SkIntToScalar(tmp.width() + 10), 0);
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}
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}
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private:
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typedef SkView INHERITED;
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};
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//////////////////////////////////////////////////////////////////////////////
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static SkView* MyFactory() { return new ExtractAlphaView; }
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static SkViewRegister reg(MyFactory);
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