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) {

[Theresa, 2017/03/31 18:05:56]

nit: JavaDoc

[Finnur, 2017/04/03 17:30:30]

Done.

+        if (bitmap == null || bitmap.getWidth() == 0 || bitmap.getHeight() == 0) {
+            return;
+        }
+
+        if (!TextUtils.equals(mRequest.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();
+        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();

[Theresa, 2017/03/31 18:05:56]

Can PickerBitmapView call initializeSpecialTile directly from #initialize() if
needed?

[Finnur, 2017/04/03 17:30:29]

When I went to make that change I realized initializeSpecialTile is used to
figure out the right (special) icon to show and calls initialize internally to
set it. Which means we don't need to call initialize at all here.

+            return;
+        }
+
+        // TODO(finnur): Use cached image, if available.
+
+        // TODO(finnur): Use decoder instead.
+        int size = mCategoryView.getImageSize();
+        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();
+    }
+}