andriod 藍牙打印問題
來源：程序員人生 發布時間：2015-05-14 09:35:47 閱讀次數：2525次
用網上的1個gprinter.jar開發藍牙與收銀機的對接打印，出現以下毛病：x + width must be <= bitmap.width()
zs這1系列的毛病都源自于矩陣的檢測：
/**
* Shared code to check for illegal arguments passed to getPixels()
* or setPixels()
*
* @param x left edge of the area of pixels to
access
* @param y top edge of the area of pixels to
access
* @param width width of the area of pixels to
access
* @param height height of the area of pixels to
access
* @param offset offset into pixels[] array
* @param stride number of elements in pixels[] between each logical row
* @param pixels array to hold the area of pixels being
accessed
*/
private void checkPixelsAccess(int x, int y, int width, int height,
int offset, int stride, int pixels[]) {
checkXYSign(x, y);
if (width < 0) {
throw new IllegalArgumentException("width must be >= 0");
}
if (height < 0) {
throw new IllegalArgumentException("height must be >= 0");
}
if (x + width > getWidth()) {
throw new IllegalArgumentException(
"x + width must be <= bitmap.width()");
}
if (y + height > getHeight()) {
throw new IllegalArgumentException(
"y + height must be <= bitmap.height()");
}
if (Math.abs(stride) < width) {
throw new IllegalArgumentException("abs(stride) must be >= width");
}
int lastScanline = offset + (height - 1) * stride;
int length = pixels.length;
if (offset < 0 || (offset + width > length)
|| lastScanline < 0
|| (lastScanline + width > length)) {
throw new ArrayIndexOutOfBoundsException();
}
}
研究了哈源代碼發現問題出在resizeImage(mBitmap, width, height);這個方法調用里面，原有方法：
<span style="color:#333333;"> public static Bitmap resizeImage(Bitmap bitmap, int w, int h)
{
Bitmap BitmapOrg = bitmap;
int width = BitmapOrg.getWidth();
int height = BitmapOrg.getHeight();
int newWidth = w;
int newHeight = h;
</span><span style="color:#ff0000;">float scaleWidth = newWidth / width;
float scaleHeight = newHeight / height;</span><span style="color:#333333;">
Matrix matrix = new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
Bitmap resizedBitmap = Bitmap.createBitmap(BitmapOrg, 0, 0, width,
height, matrix, true);
return resizedBitmap;
}</span>
這里計算的單位換算 float=int/int>>>float=int*1.0f/int就不會報錯了，否則平板上會報錯
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