嘿大家，我的代码有一点问题我做了绘图应用程序，但我有一点麻烦 大/大/大图片。我想让我的应用程序变得更有效，但是这个问题让我很生气。 好吧，我使用位图，我用画布绘制，但问题是，如果我想加载图片，并有一个问题：
java.lang.OutOfMemoryError
at android.graphics.Bitmap.nativeCreate(Native Method)
并且有代码：
public void load() {
if (mPicturePath != null) {
FileInputStream in;
BufferedInputStream buf;
try {
loadedBmp=null;
in = new FileInputStream(mPicturePath);
buf = new BufferedInputStream(in);
byte[] bMapArray = new byte[buf.available()];
buf.read(bMapArray);
loadedBmp = BitmapFactory.decodeByteArray(bMapArray, 0,
bMapArray.length);
loadedBmp = resizeImage(loadedBmp);
delete();
drawBitmap(loadedBmp);
updateBitmap(loadedBmp);
if (in != null) {
in.close();
}
if (buf != null) {
buf.close();
}
} catch (Exception e) {
Log.e("Error reading file", e.toString());
}
// Clear path so we don't load it again next time.
mPicturePath = null;
}
}
而且，对于大图片来说，sacond问题很慢，如果我崩溃，我不知道图片的边界在哪里。我无法找到解决方法:(
答案 0 :(得分：0)
要获得一个Bitmap使用Android Query，它会帮助您，不要制作解码数组或任何东西，这个很容易和有效。
从这里下载jar：http://code.google.com/p/android-query/
代码：
private AQuery androidAQuery;
androidAQuery=new AQuery(this);
androidAQuery.ajax(YOUR IMAGE URL,Bitmap.class,0,new AjaxCallback<Bitmap>(){
@Override
public void callback(String url, Bitmap object, AjaxStatus status) {
super.callback(url, object, status);
//You will get Bitmap from object.
}
});
答案 1 :(得分：0)
试试这个对我有用。
private String decodeFile(String path) {
String strMyImagePath = null;
Bitmap scaledBitmap = null;
try {
// Part 1: Decode image
Bitmap unscaledBitmap = ScalingUtilities.decodeFile(path, DESIREDWIDTH, DESIREDHEIGHT, ScalingLogic.FIT);
if (!(unscaledBitmap.getWidth() <= 800 && unscaledBitmap.getHeight() <= 800)) {
// Part 2: Scale image
scaledBitmap = ScalingUtilities.createScaledBitmap(unscaledBitmap, DESIREDWIDTH, DESIREDHEIGHT, ScalingLogic.FIT);
} else {
unscaledBitmap.recycle();
return path;
}
// Store to tmp file
String extr = Environment.getExternalStorageDirectory().toString();
File mFolder = new File(extr + "/myTmpDir");
if (!mFolder.exists()) {
mFolder.mkdir();
}
String s = "tmp.png";
File f = new File(mFolder.getAbsolutePath(), s);
strMyImagePath = f.getAbsolutePath();
FileOutputStream fos = null;
try {
fos = new FileOutputStream(f);
scaledBitmap.compress(Bitmap.CompressFormat.PNG, 70, fos);
fos.flush();
fos.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
scaledBitmap.recycle();
} catch (Throwable e) {
}
if (strMyImagePath == null) {
return path;
}
return strMyImagePath;
}
公用事业类
public class ScalingUtilities {
/**
* Utility function for decoding an image resource. The decoded bitmap will
* be optimized for further scaling to the requested destination dimensions
* and scaling logic.
*
* @param res The resources object containing the image data
* @param resId The resource id of the image data
* @param dstWidth Width of destination area
* @param dstHeight Height of destination area
* @param scalingLogic Logic to use to avoid image stretching
* @return Decoded bitmap
*/
public static Bitmap decodeResource(Resources res, int resId, int dstWidth, int dstHeight,
ScalingLogic scalingLogic) {
Options options = new Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(res, resId, options);
options.inJustDecodeBounds = false;
options.inSampleSize = calculateSampleSize(options.outWidth, options.outHeight, dstWidth,
dstHeight, scalingLogic);
Bitmap unscaledBitmap = BitmapFactory.decodeResource(res, resId, options);
return unscaledBitmap;
}
public static Bitmap decodeFile(String path, int dstWidth, int dstHeight,
ScalingLogic scalingLogic) {
Options options = new Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(path, options);
options.inJustDecodeBounds = false;
options.inSampleSize = calculateSampleSize(options.outWidth, options.outHeight, dstWidth,
dstHeight, scalingLogic);
Bitmap unscaledBitmap = BitmapFactory.decodeFile(path, options);
return unscaledBitmap;
}
/**
* Utility function for creating a scaled version of an existing bitmap
*
* @param unscaledBitmap Bitmap to scale
* @param dstWidth Wanted width of destination bitmap
* @param dstHeight Wanted height of destination bitmap
* @param scalingLogic Logic to use to avoid image stretching
* @return New scaled bitmap object
*/
public static Bitmap createScaledBitmap(Bitmap unscaledBitmap, int dstWidth, int dstHeight,
ScalingLogic scalingLogic) {
Rect srcRect = calculateSrcRect(unscaledBitmap.getWidth(), unscaledBitmap.getHeight(),
dstWidth, dstHeight, scalingLogic);
Rect dstRect = calculateDstRect(unscaledBitmap.getWidth(), unscaledBitmap.getHeight(),
dstWidth, dstHeight, scalingLogic);
Bitmap scaledBitmap = Bitmap.createBitmap(dstRect.width(), dstRect.height(),
Config.ARGB_8888);
Canvas canvas = new Canvas(scaledBitmap);
canvas.drawBitmap(unscaledBitmap, srcRect, dstRect, new Paint(Paint.FILTER_BITMAP_FLAG));
return scaledBitmap;
}
/**
* ScalingLogic defines how scaling should be carried out if source and
* destination image has different aspect ratio.
*
* CROP: Scales the image the minimum amount while making sure that at least
* one of the two dimensions fit inside the requested destination area.
* Parts of the source image will be cropped to realize this.
*
* FIT: Scales the image the minimum amount while making sure both
* dimensions fit inside the requested destination area. The resulting
* destination dimensions might be adjusted to a smaller size than
* requested.
*/
public static enum ScalingLogic {
CROP, FIT
}
/**
* Calculate optimal down-sampling factor given the dimensions of a source
* image, the dimensions of a destination area and a scaling logic.
*
* @param srcWidth Width of source image
* @param srcHeight Height of source image
* @param dstWidth Width of destination area
* @param dstHeight Height of destination area
* @param scalingLogic Logic to use to avoid image stretching
* @return Optimal down scaling sample size for decoding
*/
public static int calculateSampleSize(int srcWidth, int srcHeight, int dstWidth, int dstHeight,
ScalingLogic scalingLogic) {
if (scalingLogic == ScalingLogic.FIT) {
final float srcAspect = (float)srcWidth / (float)srcHeight;
final float dstAspect = (float)dstWidth / (float)dstHeight;
if (srcAspect > dstAspect) {
return srcWidth / dstWidth;
} else {
return srcHeight / dstHeight;
}
} else {
final float srcAspect = (float)srcWidth / (float)srcHeight;
final float dstAspect = (float)dstWidth / (float)dstHeight;
if (srcAspect > dstAspect) {
return srcHeight / dstHeight;
} else {
return srcWidth / dstWidth;
}
}
}
/**
* Calculates source rectangle for scaling bitmap
*
* @param srcWidth Width of source image
* @param srcHeight Height of source image
* @param dstWidth Width of destination area
* @param dstHeight Height of destination area
* @param scalingLogic Logic to use to avoid image stretching
* @return Optimal source rectangle
*/
public static Rect calculateSrcRect(int srcWidth, int srcHeight, int dstWidth, int dstHeight,
ScalingLogic scalingLogic) {
if (scalingLogic == ScalingLogic.CROP) {
final float srcAspect = (float)srcWidth / (float)srcHeight;
final float dstAspect = (float)dstWidth / (float)dstHeight;
if (srcAspect > dstAspect) {
final int srcRectWidth = (int)(srcHeight * dstAspect);
final int srcRectLeft = (srcWidth - srcRectWidth) / 2;
return new Rect(srcRectLeft, 0, srcRectLeft + srcRectWidth, srcHeight);
} else {
final int srcRectHeight = (int)(srcWidth / dstAspect);
final int scrRectTop = (int)(srcHeight - srcRectHeight) / 2;
return new Rect(0, scrRectTop, srcWidth, scrRectTop + srcRectHeight);
}
} else {
return new Rect(0, 0, srcWidth, srcHeight);
}
}
/**
* Calculates destination rectangle for scaling bitmap
*
* @param srcWidth Width of source image
* @param srcHeight Height of source image
* @param dstWidth Width of destination area
* @param dstHeight Height of destination area
* @param scalingLogic Logic to use to avoid image stretching
* @return Optimal destination rectangle
*/
public static Rect calculateDstRect(int srcWidth, int srcHeight, int dstWidth, int dstHeight,
ScalingLogic scalingLogic) {
if (scalingLogic == ScalingLogic.FIT) {
final float srcAspect = (float)srcWidth / (float)srcHeight;
final float dstAspect = (float)dstWidth / (float)dstHeight;
if (srcAspect > dstAspect) {
return new Rect(0, 0, dstWidth, (int)(dstWidth / srcAspect));
} else {
return new Rect(0, 0, (int)(dstHeight * srcAspect), dstHeight);
}
} else {
return new Rect(0, 0, dstWidth, dstHeight);
}
}
}