Implement the new Photo picker, part two.

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

+// Copyright 2017 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 java.util.List;
+
+/**
+ * Holds on to a {@link PickerBitmapView} 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 mBitmapDetails;
+
+    /**
+     * The PickerBitmapViewHolder.
+     * @param itemView The {@link PickerBitmapView} view for showing the image.
+     */
+    public PickerBitmapViewHolder(PickerBitmapView itemView) {
+        super(itemView);
+        mItemView = itemView;
+    }
+
+    /**
+     * The notification handler for when an image has been decoded.
+     * @param filePath The file path for the newly decoded image.
+     * @param bitmap The results of the decoding (or placeholder image, if failed).
+     */
+    public void imageDecodedCallback(String filePath, Bitmap bitmap) {
+        if (bitmap == null || bitmap.getWidth() == 0 || bitmap.getHeight() == 0) {
+            return;
+        }
+
+        if (!TextUtils.equals(mBitmapDetails.getFilePath(), filePath)) {
+            return;
+        }
+
+        mItemView.setThumbnailBitmap(bitmap);
+    }
+
+    /**
+     * 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();
+        mBitmapDetails = pickerBitmaps.get(position);
+
+        String filePath = mBitmapDetails.getFilePath();

[Theresa, 2017/04/06 15:15:29]

nit: findbugs reported a deadstore for this variable

[Finnur, 2017/04/06 15:46:47]

Done.

+        if (mBitmapDetails.type() == PickerBitmap.TileTypes.CAMERA
+                || mBitmapDetails.type() == PickerBitmap.TileTypes.GALLERY) {
+            mItemView.initializeSpecialTile(mBitmapDetails);
+            return;
+        }
+
+        // TODO(finnur): Use cached image, if available.
+
+        // TODO(finnur): Use decoder instead.
+        int size = mCategoryView.getImageSize();
+        imageDecodedCallback(mBitmapDetails.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 mBitmapDetails == null ? null : mBitmapDetails.getFilePath();
+    }
+}