安卓开发中Bitmap源码实例
package android.graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import javax.imageio.ImageIO;
public final class Bitmap extends _Original_Bitmap {
private BufferedImage mImage;
public Bitmap(File input) throws IOException {
super(1, true, null, -1);
mImage = ImageIO.read(input);
}
public Bitmap(InputStream is) throws IOException {
super(1, true, null, -1);
mImage = ImageIO.read(is);
}
Bitmap(BufferedImage image) {
super(1, true, null, -1);
mImage = image;
}
public BufferedImage getImage() {
return mImage;
}
// ----- overriden methods
public enum Config {
// these native values must match up with the enum in SkBitmap.h
ALPHA_8 (2),
RGB_565 (4),
ARGB_4444 (5),
ARGB_8888 (6);
Config(int ni) {
this.nativeInt = ni;
}
final int nativeInt;
/* package */ static Config nativeToConfig(int ni) {
return sConfigs[ni];
}
private static Config sConfigs[] = {
null, null, ALPHA_8, null, RGB_565, ARGB_4444, ARGB_8888
};
}
@Override
public int getWidth() {
return mImage.getWidth();
}
@Override
public int getHeight() {
return mImage.getHeight();
}
/**
* Returns an immutable bitmap from the source bitmap. The new bitmap may
* be the same object as source, or a copy may have been made.
*/
public static Bitmap createBitmap(Bitmap src) {
return createBitmap(src, 0, 0, src.getWidth(), src.getHeight(), null, false);
}
/**
* Returns an immutable bitmap from the specified subset of the source
* bitmap. The new bitmap may be the same object as source, or a copy may
* have been made.
*
* @param source The bitmap we are subsetting
* @param x The x coordinate of the first pixel in source
* @param y The y coordinate of the first pixel in source
* @param width The number of pixels in each row
* @param height The number of rows
*/
public static Bitmap createBitmap(Bitmap source, int x, int y,
int width, int height) {
return new Bitmap(source.mImage.getSubimage(x, y, width, height));
}
/**
* Returns an immutable bitmap from subset of the source bitmap,
* transformed by the optional matrix.
*
* @param source The bitmap we are subsetting
* @param x The x coordinate of the first pixel in source
* @param y The y coordinate of the first pixel in source
* @param width The number of pixels in each row
* @param height The number of rows
* @param m Option matrix to be applied to the pixels
* @param filter true if the source should be filtered.
* Only applies if the matrix contains more than just
* translation.
* @return A bitmap that represents the specified subset of source
* @throws IllegalArgumentException if the x, y, width, height values are
* outside of the dimensions of the source bitmap.
*/
public static Bitmap createBitmap(Bitmap source, int x, int y, int width,
int height, Matrix m, boolean filter) {
checkXYSign(x, y);
checkWidthHeight(width, height);
if (x + width > source.getWidth()) {
throw new IllegalArgumentException(
"x + width must be <= bitmap.width()");
}
if (y + height > source.getHeight()) {
throw new IllegalArgumentException(
"y + height must be <= bitmap.height()");
}
// check if we can just return our argument unchanged
if (!source.isMutable() && x == 0 && y == 0
&& width == source.getWidth() && height == source.getHeight()
&& (m == null || m.isIdentity())) {
return source;
}
if (m == null || m.isIdentity()) {
return new Bitmap(source.mImage.getSubimage(x, y, width, height));
}
int neww = width;
int newh = height;
Paint paint;
Rect srcR = new Rect(x, y, x + width, y + height);
RectF dstR = new RectF(0, 0, width, height);
/* the dst should have alpha if the src does, or if our matrix
doesn't preserve rectness
*/
boolean hasAlpha = source.hasAlpha() || !m.rectStaysRect();
RectF deviceR = new RectF();
m.mapRect(deviceR, dstR);
neww = Math.round(deviceR.width());
newh = Math.round(deviceR.height());
Canvas canvas = new Canvas(neww, newh);
canvas.translate(-deviceR.left, -deviceR.top);
canvas.concat(m);
paint = new Paint();
paint.setFilterBitmap(filter);
if (!m.rectStaysRect()) {
paint.setAntiAlias(true);
}
canvas.drawBitmap(source, srcR, dstR, paint);
return new Bitmap(canvas.getImage());
}
/**
* Returns a mutable bitmap with the specified width and height.
*
* @param width The width of the bitmap
* @param height The height of the bitmap
* @param config The bitmap config to create.
* @throws IllegalArgumentException if the width or height are <= 0
*/
public static Bitmap createBitmap(int width, int height, Config config) {
return new Bitmap(new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB));
}
/**
* Returns a immutable bitmap with the specified width and height, with each
* pixel value set to the corresponding value in the colors array.
*
* @param colors Array of {@link Color} used to initialize the pixels.
* @param offset Number of values to skip before the first color in the
* array of colors.
* @param stride Number of colors in the array between rows (must be >=
* width or <= -width).
* @param width The width of the bitmap
* @param height The height of the bitmap
* @param config The bitmap config to create. If the config does not
* support per-pixel alpha (e.g. RGB_565), then the alpha
* bytes in the colors[] will be ignored (assumed to be FF)
* @throws IllegalArgumentException if the width or height are <= 0, or if
* the color array's length is less than the number of pixels.
*/
public static Bitmap createBitmap(int colors[], int offset, int stride,
int width, int height, Config config) {
checkWidthHeight(width, height);
if (Math.abs(stride) < width) {
throw new IllegalArgumentException("abs(stride) must be >= width");
}
int lastScanline = offset + (height - 1) * stride;
int length = colors.length;
if (offset < 0 || (offset + width > length)
|| lastScanline < 0
|| (lastScanline + width > length)) {
throw new ArrayIndexOutOfBoundsException();
}
// TODO: create an immutable bitmap...
throw new UnsupportedOperationException();
}
/**
* Returns a immutable bitmap with the specified width and height, with each
* pixel value set to the corresponding value in the colors array.
*
* @param colors Array of {@link Color} used to initialize the pixels.
* This array must be at least as large as width * height.
* @param width The width of the bitmap
* @param height The height of the bitmap
* @param config The bitmap config to create. If the config does not
* support per-pixel alpha (e.g. RGB_565), then the alpha
* bytes in the colors[] will be ignored (assumed to be FF)
* @throws IllegalArgumentException if the width or height are <= 0, or if
* the color array's length is less than the number of pixels.
*/
public static Bitmap createBitmap(int colors[], int width, int height,
Config config) {
return createBitmap(colors, 0, width, width, height, config);
}
public static Bitmap createScaledBitmap(Bitmap src, int dstWidth,
int dstHeight, boolean filter) {
Matrix m;
synchronized (Bitmap.class) {
// small pool of just 1 matrix
m = sScaleMatrix;
sScaleMatrix = null;
}
if (m == null) {
m = new Matrix();
}
final int width = src.getWidth();
final int height = src.getHeight();
final float sx = dstWidth / (float)width;
final float sy = dstHeight / (float)height;
m.setScale(sx, sy);
Bitmap b = Bitmap.createBitmap(src, 0, 0, width, height, m, filter);
synchronized (Bitmap.class) {
// do we need to check for null? why not just assign everytime?
if (sScaleMatrix == null) {
sScaleMatrix = m;
}
}
return b;
}
}
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