Implement the new Photo picker, part two.

chrome/android/java/src/org/chromium/chrome/browser/photo_picker/PickerBitmapViewHolder.java

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.photo_picker;
+
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
+import android.support.v7.widget.RecyclerView.ViewHolder;
+import android.text.TextUtils;
+import android.view.View;
+
+import java.util.List;
+
+/**
+ * Holds onto a View that displays information about a picker bitmap.
+ */
+public class PickerBitmapViewHolder extends ViewHolder {
+    // Our parent category.
+    private PickerCategoryView mCategoryView;
+
+    // The bitmap view we are holding on to.
+    private final PickerBitmapView mItemView;
+
+    // The request we are showing the bitmap for.
+    private PickerBitmap mRequest;
+
+    /**
+     * The PickerBitmapViewHolder.
+     * @param itemView The PickerBitmap view for showing the image.
+     */
+    public PickerBitmapViewHolder(View itemView) {
+        super(itemView);
+
+        assert itemView instanceof PickerBitmapView;
+        mItemView = (PickerBitmapView) itemView;
+    }
+
+    public void imageDecodedCallback(String filePath, Bitmap bitmap) {
+        if (bitmap == null || bitmap.getWidth() == 0 || bitmap.getHeight() == 0) {
+            return;
+        }
+
+        if (mCategoryView.getHighResBitmaps().get(filePath) == null) {
+            mCategoryView.getHighResBitmaps().put(filePath, bitmap);
+        }
+
+        if (mCategoryView.getLowResBitmaps().get(filePath) == null) {
+            // Scaling the image down takes between 0-1 ms on average (Nexus 6 phone debug build).
+            Bitmap lowres = BitmapUtils.scale(bitmap, 40, false);
+            mCategoryView.getLowResBitmaps().put(filePath, lowres);
+        }
+
+        if (!TextUtils.equals(mRequest.getFilePath(), filePath)) {
+            return;
+        }
+
+        if (mItemView.setThumbnailBitmap(bitmap)) {
+            mItemView.fadeInThumbnail();
+        }
+    }
+
+    /**
+     * Display a single item from |position| in the PickerCategoryView.
+     * @param categoryView The PickerCategoryView to use to fetch the image.
+     * @param position The position of the item to fetch.
+     */
+    public void displayItem(PickerCategoryView categoryView, int position) {
+        mCategoryView = categoryView;
+
+        List<PickerBitmap> pickerBitmaps = mCategoryView.getPickerBitmaps();
+        mRequest = pickerBitmaps.get(position);
+
+        String filePath = mRequest.getFilePath();
+        if (mRequest.type() == PickerBitmap.TileTypes.CAMERA
+                || mRequest.type() == PickerBitmap.TileTypes.GALLERY) {
+            mItemView.initialize(mRequest, null, false);
+            mItemView.initializeSpecialTile();
+            return;
+        }
+
+        Bitmap original = mCategoryView.getHighResBitmaps().get(filePath);
+        if (original != null) {
+            mItemView.initialize(mRequest, original, false);
+            return;
+        }
+
+        int size = mCategoryView.getImageSize();
+        Bitmap placeholder = mCategoryView.getLowResBitmaps().get(filePath);
+        if (placeholder != null) {
+            // Scaling the image up takes between 3-4 ms on average (Nexus 6 phone debug build).
+            placeholder = BitmapUtils.scale(placeholder, size, false);
+            mItemView.initialize(mRequest, placeholder, false);
+        } else {
+            placeholder = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888);
+            placeholder.eraseColor(Color.argb(0, 0, 0, 0));
+            mItemView.initialize(mRequest, placeholder, true);
+        }
+
+        // TODO(finnur): Use decoder.
+        imageDecodedCallback(mRequest.getFilePath(), createPlaceholderBitmap(size, size));
+    }
+
+    /**
+     * Creates a placeholder bitmap.
+     * @param width The requested width of the resulting bitmap.
+     * @param height The requested height of the resulting bitmap.
+     * @return Placeholder bitmap.
+     */
+    // TODO(finnur): Remove once the decoder is in place.
+    private Bitmap createPlaceholderBitmap(int width, int height) {
+        Bitmap placeholder = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
+        Canvas canvas = new Canvas(placeholder);
+        Paint paint = new Paint();
+        paint.setColor(Color.GRAY);
+        canvas.drawRect(0, 0, (float) width, (float) height, paint);
+        return placeholder;
+    }
+
+    /**
+     * Returns the file path of the current request.
+     */
+    public String getFilePath() {
+        return mRequest == null ? null : mRequest.getFilePath();
+    }
+}