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技術社區[雲棲]
cocos2d-x中使圖片背景全透明（另一種方法）
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CCLayerColor::initWithColor(ccc4(255,255,255,255));
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CCImage *pImage = new CCImage();
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pImage->autorelease();
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pImage->initWithImageFile("arraw.png",CCImage::EImageFormat::kFmtPng);
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//遍曆圖片的所有像素.
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unsigned char *pData = pImage->getData();
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int nPixelIndex = 0;
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for (int nCol = 0; nCol < pImage->getHeight(); nCol ++)
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{
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for (int nRow = 0; nRow < pImage->getWidth(); nRow ++)
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{
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//取圖片的RGB值.
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int nBeginPos = nPixelIndex;
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unsigned int nRValue = pData[nPixelIndex];
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nPixelIndex++;
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unsigned int nGValue = pData[nPixelIndex];
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nPixelIndex ++;
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unsigned int nBValue = pData[nPixelIndex];
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nPixelIndex ++;
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unsigned int nAValue = pData[nPixelIndex];
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nPixelIndex ++;
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int nAlphaRatio = 0;
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//本代碼的核心:取RGB中的最大值賦給nAlphaRatio。如果nAlphaRatio為0,則像素中的alpha通道就為0,否則像素中的
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//alpha通道值就是nAlphaRatio。這樣做是為了在圖片中顏色漸變過渡比較大的區域實現平滑的過渡。讓最終形成的
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//圖片看起來不粗糙.
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nAlphaRatio = nRValue>nGValue?(nRValue>nBValue?nRValue:nBValue):(nGValue>nBValue?nGValue:nBValue);
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if(nAlphaRatio != 0)
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{
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nAValue = nAlphaRatio;
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}
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else
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{
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nAValue= 0;
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}
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pData[nBeginPos] = (unsigned
char)nRValue;
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pData[nBeginPos+ 1] = (unsigned
char)nGValue;
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pData[nBeginPos + 2] = (unsigned
char)nBValue;
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//修改原圖的alpha值.
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pData[nBeginPos + 3] = (unsigned
char)nAValue;
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}
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}
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CCTexture2D *pTexture = new CCTexture2D;
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pTexture->autorelease();
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pTexture->initWithImage(pImage);
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CCTexture2DPixelFormat ccpf = pTexture->getPixelFormat();
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CCAssert(ccpf == kTexture2DPixelFormat_RGBA8888, "your
png file's pixel format is not RGBA8888 or not have alpha panel");
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CCSprite* pArrowSprite= new CCSprite();
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pArrowSprite->initWithTexture(pTexture);
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CCSize size = CCDirector::sharedDirector()->getWinSize();
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pArrowSprite->setPosition(ccp(size.width/2 + 20, size.height/2 - 20));
- this->addChild(pArrowSprite, 6);
直接看代碼注釋就懂了。貼上效果圖，打完收工。
最後更新：2017-04-03 12:56:43