1 files changed, 99 insertions, 0 deletions
diff --git a/samples/devbytes/graphics/BitmapAllocation/src/com/example/android/bitmapallocation/BitmapAllocation.java b/samples/devbytes/graphics/BitmapAllocation/src/com/example/android/bitmapallocation/BitmapAllocation.java
new file mode 100644
index 000000000..cc6b1e00a
--- /dev/null
+++ b/samples/devbytes/graphics/BitmapAllocation/src/com/example/android/bitmapallocation/BitmapAllocation.java
@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2013 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 com.example.android.bitmapallocation;
+
+import android.app.Activity;
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
+import android.os.Bundle;
+import android.view.View;
+import android.widget.CheckBox;
+import android.widget.ImageView;
+import android.widget.TextView;
+
+/**
+ * This example shows how to speed up bitmap loading and reduce garbage collection
+ * by reusing existing bitmaps.
+ *
+ * Watch the associated video for this demo on the DevBytes channel of developer.android.com,
+ * or on YouTube at https://www.youtube.com/watch?v=rsQet4nBVi8.
+ */
+public class BitmapAllocation extends Activity {
+
+    // There are some assumptions in this demo app that don't carry over well to the real world:
+    // it assumes that all bitmaps are the same size and that loading all bitmaps as the activity
+    // starts is good enough. A real application would be take a more flexible and robust
+    // approach. But these assumptions are good enough for the purposes of this tutorial,
+    // which is about reusing existing bitmaps of the same size.
+
+    int mCurrentIndex = 0;
+    Bitmap mCurrentBitmap = null;
+    BitmapFactory.Options mBitmapOptions;
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_bitmap_allocation);
+
+        final int[] imageIDs = {R.drawable.a, R.drawable.b, R.drawable.c, R.drawable.d,
+                R.drawable.e, R.drawable.f};
+
+        final CheckBox checkbox = (CheckBox) findViewById(R.id.checkbox);
+        final TextView durationTextview = (TextView) findViewById(R.id.loadDuration);
+        final ImageView imageview = (ImageView) findViewById(R.id.imageview);
+
+        // Create bitmap to be re-used, based on the size of one of the bitmaps
+        mBitmapOptions = new BitmapFactory.Options();
+        mBitmapOptions.inJustDecodeBounds = true;
+        BitmapFactory.decodeResource(getResources(), R.drawable.a, mBitmapOptions);
+        mCurrentBitmap = Bitmap.createBitmap(mBitmapOptions.outWidth,
+                mBitmapOptions.outHeight, Bitmap.Config.ARGB_8888);
+        mBitmapOptions.inJustDecodeBounds = false;
+        mBitmapOptions.inBitmap = mCurrentBitmap;
+        mBitmapOptions.inSampleSize = 1;
+        BitmapFactory.decodeResource(getResources(), R.drawable.a, mBitmapOptions);
+        imageview.setImageBitmap(mCurrentBitmap);
+
+        // When the user clicks on the image, load the next one in the list
+        imageview.setOnClickListener(new View.OnClickListener() {
+
+            @Override
+            public void onClick(View v) {
+                mCurrentIndex = (mCurrentIndex + 1) % imageIDs.length;
+                BitmapFactory.Options bitmapOptions = null;
+                if (checkbox.isChecked()) {
+                    // Re-use the bitmap by using BitmapOptions.inBitmap
+                    bitmapOptions = mBitmapOptions;
+                    bitmapOptions.inBitmap = mCurrentBitmap;
+                }
+                long startTime = System.currentTimeMillis();
+                mCurrentBitmap = BitmapFactory.decodeResource(getResources(),
+                        imageIDs[mCurrentIndex], bitmapOptions);
+                imageview.setImageBitmap(mCurrentBitmap);
+
+                // One way you can see the difference between reusing and not is through the
+                // timing reported here. But you can also see a huge impact in the garbage
+                // collector if you look at logcat with and without reuse. Avoiding garbage
+                // collection when possible, especially for large items like bitmaps,
+                // is always a good idea.
+                durationTextview.setText("Load took " +
+                        (System.currentTimeMillis() - startTime));
+            }
+        });
+    }
+
+}