/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.graphics;
import java.io.InputStream;
import java.io.OutputStream;
/**
* A Picture records drawing calls (via the canvas returned by beginRecording)
* and can then play them back into Canvas (via {@link Picture#draw(Canvas)} or
* {@link Canvas#drawPicture(Picture)}).For most content (e.g. text, lines, rectangles),
* drawing a sequence from a picture can be faster than the equivalent API
* calls, since the picture performs its playback without incurring any
* method-call overhead.
*/
public class Picture {
private Canvas mRecordingCanvas;
private final long mNativePicture;
private static final int WORKING_STREAM_STORAGE = 16 * 1024;
/**
* Creates an empty picture that is ready to record.
*/
public Picture() {
this(nativeConstructor(0));
}
/**
* Create a picture by making a copy of what has already been recorded in
* src. The contents of src are unchanged, and if src changes later, those
* changes will not be reflected in this picture.
*/
public Picture(Picture src) {
this(nativeConstructor(src != null ? src.mNativePicture : 0));
}
private Picture(long nativePicture) {
if (nativePicture == 0) {
throw new RuntimeException();
}
mNativePicture = nativePicture;
}
@Override
protected void finalize() throws Throwable {
try {
nativeDestructor(mNativePicture);
} finally {
super.finalize();
}
}
/**
* To record a picture, call beginRecording() and then draw into the Canvas
* that is returned. Nothing we appear on screen, but all of the draw
* commands (e.g. {@link Canvas#drawRect(Rect, Paint)}) will be recorded.
* To stop recording, call endRecording(). After endRecording() the Canvas
* that was returned must no longer be used, and nothing should be drawn
* into it.
*/
public Canvas beginRecording(int width, int height) {
long ni = nativeBeginRecording(mNativePicture, width, height);
mRecordingCanvas = new RecordingCanvas(this, ni);
return mRecordingCanvas;
}
/**
* Call endRecording when the picture is built. After this call, the picture
* may be drawn, but the canvas that was returned by beginRecording must not
* be used anymore. This is automatically called if {@link Picture#draw}
* or {@link Canvas#drawPicture(Picture)} is called.
*/
public void endRecording() {
if (mRecordingCanvas != null) {
mRecordingCanvas = null;
nativeEndRecording(mNativePicture);
}
}
/**
* Get the width of the picture as passed to beginRecording. This
* does not reflect (per se) the content of the picture.
*/
public int getWidth() {
return nativeGetWidth(mNativePicture);
}
/**
* Get the height of the picture as passed to beginRecording. This
* does not reflect (per se) the content of the picture.
*/
public int getHeight() {
return nativeGetHeight(mNativePicture);
}
/**
* Draw this picture on the canvas.
* <p>
* Prior to {@link android.os.Build.VERSION_CODES#LOLLIPOP}, this call could
* have the side effect of changing the matrix and clip of the canvas
* if this picture had imbalanced saves/restores.
*
* <p>
* <strong>Note:</strong> This forces the picture to internally call
* {@link Picture#endRecording()} in order to prepare for playback.
*
* @param canvas The picture is drawn to this canvas
*/
public void draw(Canvas canvas) {
if (canvas.isHardwareAccelerated()) {
throw new IllegalArgumentException(
"Picture playback is only supported on software canvas.");
}
if (mRecordingCanvas != null) {
endRecording();
}
nativeDraw(canvas.getNativeCanvasWrapper(), mNativePicture);
}
/**
* Create a new picture (already recorded) from the data in the stream. This
* data was generated by a previous call to writeToStream(). Pictures that
* have been persisted across device restarts are not guaranteed to decode
* properly and are highly discouraged.
*
* <p>
* <strong>Note:</strong> a picture created from an input stream cannot be
* replayed on a hardware accelerated canvas.
*
* @see #writeToStream(java.io.OutputStream)
* @deprecated The recommended alternative is to not use writeToStream and
* instead draw the picture into a Bitmap from which you can persist it as
* raw or compressed pixels.
*/
@Deprecated
public static Picture createFromStream(InputStream stream) {
return new Picture(nativeCreateFromStream(stream, new byte[WORKING_STREAM_STORAGE]));
}
/**
* Write the picture contents to a stream. The data can be used to recreate
* the picture in this or another process by calling createFromStream(...)
* The resulting stream is NOT to be persisted across device restarts as
* there is no guarantee that the Picture can be successfully reconstructed.
*
* <p>
* <strong>Note:</strong> a picture created from an input stream cannot be
* replayed on a hardware accelerated canvas.
*
* @see #createFromStream(java.io.InputStream)
* @deprecated The recommended alternative is to draw the picture into a
* Bitmap from which you can persist it as raw or compressed pixels.
*/
@Deprecated
public void writeToStream(OutputStream stream) {
// do explicit check before calling the native method
if (stream == null) {
throw new NullPointerException();
}
if (!nativeWriteToStream(mNativePicture, stream,
new byte[WORKING_STREAM_STORAGE])) {
throw new RuntimeException();
}
}
// return empty picture if src is 0, or a copy of the native src
private static native long nativeConstructor(long nativeSrcOr0);
private static native long nativeCreateFromStream(InputStream stream, byte[] storage);
private static native int nativeGetWidth(long nativePicture);
private static native int nativeGetHeight(long nativePicture);
private static native long nativeBeginRecording(long nativeCanvas, int w, int h);
private static native void nativeEndRecording(long nativeCanvas);
private static native void nativeDraw(long nativeCanvas, long nativePicture);
private static native boolean nativeWriteToStream(long nativePicture,
OutputStream stream, byte[] storage);
private static native void nativeDestructor(long nativePicture);
private static class RecordingCanvas extends Canvas {
private final Picture mPicture;
public RecordingCanvas(Picture pict, long nativeCanvas) {
super(nativeCanvas);
mPicture = pict;
}
@Override
public void setBitmap(Bitmap bitmap) {
throw new RuntimeException("Cannot call setBitmap on a picture canvas");
}
@Override
public void drawPicture(Picture picture) {
if (mPicture == picture) {
throw new RuntimeException("Cannot draw a picture into its recording canvas");
}
super.drawPicture(picture);
}
}
}
|
