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Diffstat (limited to 'graphics/java/android/graphics/Picture.java')
| -rw-r--r-- | graphics/java/android/graphics/Picture.java | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/graphics/java/android/graphics/Picture.java b/graphics/java/android/graphics/Picture.java new file mode 100644 index 0000000..bbb2dbf --- /dev/null +++ b/graphics/java/android/graphics/Picture.java @@ -0,0 +1,176 @@ +/* + * 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 (via picture.draw(canvas) or canvas.drawPicture). + * The picture's contents can also be written to a stream, and then later + * restored to a new picture (via writeToStream / createFromStream). For most + * content (esp. 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 java-call overhead. + */ +public class Picture { + private Canvas mRecordingCanvas; + private final int mNativePicture; + + private static final int WORKING_STREAM_STORAGE = 16 * 1024; + + 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)); + } + + /** + * 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. drawRect(...)) will be recorded. To stop recording, call + * endRecording(). At this point the Canvas that was returned must no longer + * be referenced, and nothing should be drawn into it. + */ + public Canvas beginRecording(int width, int height) { + int 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 referenced anymore. This is automatically called if Picture.draw() or + * Canvas.drawPicture() 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 native int getWidth(); + + /** + * Get the height of the picture as passed to beginRecording. This + * does not reflect (per se) the content of the picture. + */ + public native int getHeight(); + + /** + * Draw this picture on the canvas. The picture may have the side effect + * of changing the matrix and clip of the canvas. + * + * @param canvas The picture is drawn to this canvas + */ + public void draw(Canvas canvas) { + if (mRecordingCanvas != null) { + endRecording(); + } + nativeDraw(canvas.mNativeCanvas, mNativePicture); + } + + /** + * Create a new picture (already recorded) from the data in the stream. This + * data was generated by a previous call to writeToStream(). + */ + 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. + */ + 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(); + } + } + + protected void finalize() throws Throwable { + nativeDestructor(mNativePicture); + } + + /*package*/ final int ni() { + return mNativePicture; + } + + private Picture(int nativePicture) { + if (nativePicture == 0) { + throw new RuntimeException(); + } + mNativePicture = nativePicture; + } + + // return empty picture if src is 0, or a copy of the native src + private static native int nativeConstructor(int nativeSrcOr0); + private static native int nativeCreateFromStream(InputStream stream, + byte[] storage); + private static native int nativeBeginRecording(int nativeCanvas, + int w, int h); + private static native void nativeEndRecording(int nativeCanvas); + private static native void nativeDraw(int nativeCanvas, int nativePicture); + private static native boolean nativeWriteToStream(int nativePicture, + OutputStream stream, byte[] storage); + private static native void nativeDestructor(int nativePicture); + + private static class RecordingCanvas extends Canvas { + private final Picture mPicture; + + public RecordingCanvas(Picture pict, int 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); + } + } +} + |