84 lines
2.8 KiB
C++
84 lines
2.8 KiB
C++
#include "blowUp.h"
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#include <string.h>
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void blowupOntoScreen( Uint32 *inImage, int inWidth, int inHeight,
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int inBlowFactor, Uint32 *inScreenPixels,
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int inScreenWidth, int inScreenHeight ) {
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int newWidth = inBlowFactor * inWidth;
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int newHeight = inBlowFactor * inHeight;
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int yOffset = ( inScreenHeight - newHeight ) / 2;
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// "up" a bit more on iPhone to make room for touch widget
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int xOffset = 2 * ( inScreenWidth - newWidth ) / 3;
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// pitch equals width for iPhone implementation
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int scanlineWidth = inScreenWidth;
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Uint32 *pixels = inScreenPixels;
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// looping across the smaller image, instead of across the larger screen,
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// was discovered using the profiler.
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// an entire screen row is repeated inBlowFactor times down the screen
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// (as a row of pixel boxes)
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// Thus, we can offload a lot more work onto memcpy if we assemble one
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// of these rows and then memcpy it onto the screen inBlowFactor times
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for( int y=0; y<inHeight; y++ ) {
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Uint32 *screenRow = new Uint32[ newWidth ];
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// flip image vertically for iPhone
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int gameY = (inHeight - 1) - y;
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// fill the screen row with rows from the pixel boxes
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for( int x=0; x<inWidth; x++ ) {
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Uint32 pixelValue = inImage[ gameY * inWidth + x ];
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// swap red and blue on iPhone
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unsigned char red = (pixelValue >> 16) & 0xFF;
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unsigned char green = (pixelValue >> 8) & 0xFF;
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unsigned char blue = (pixelValue >> 0) & 0xFF;
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pixelValue = blue << 16 | green << 8 | red;
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// spread this pixel across an inBlowFactor-wide box row in
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// the screen row
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int boxXStart = inBlowFactor * x;
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int boxXEnd = boxXStart + inBlowFactor;
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// make an array to represent one row of this box
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// we can thus replace the inner loop with a memcpy below
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for( int i=boxXStart; i<boxXEnd; i++ ) {
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screenRow[i] = pixelValue;
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}
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}
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// now copy the row onto the screen inBlowFactor times
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int screenRowStart = ( yOffset + y * inBlowFactor ) * scanlineWidth
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+ xOffset;
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int screenRowEnd = screenRowStart + inBlowFactor * scanlineWidth;
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int screenRowIncrement = scanlineWidth;
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for( int screenRowIndex = screenRowStart;
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screenRowIndex < screenRowEnd;
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screenRowIndex += screenRowIncrement ) {
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memcpy( &( pixels[ screenRowIndex ] ),
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screenRow, newWidth * 4 );
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}
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delete [] screenRow;
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}
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}
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