PrintPreviewController.java revision 13f542cabd635c55ade5442764cc4a3d2f7880ea 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.printspooler.ui;
18
19import android.os.Handler;
20import android.os.Looper;
21import android.os.Message;
22import android.os.ParcelFileDescriptor;
23import android.print.PageRange;
24import android.print.PrintAttributes.MediaSize;
25import android.print.PrintAttributes.Margins;
26import android.print.PrintDocumentInfo;
27import android.support.v7.widget.OrientationHelper;
28import android.support.v7.widget.RecyclerView;
29import android.support.v7.widget.RecyclerView.ViewHolder;
30import android.support.v7.widget.RecyclerView.LayoutManager;
31import android.support.v7.widget.StaggeredGridLayoutManager;
32import android.view.View;
33import com.android.internal.os.SomeArgs;
34import com.android.printspooler.R;
35import com.android.printspooler.model.MutexFileProvider;
36import com.android.printspooler.widget.PrintContentView;
37import com.android.printspooler.widget.EmbeddedContentContainer;
38import com.android.printspooler.widget.PrintOptionsLayout;
39
40import java.io.File;
41import java.io.FileNotFoundException;
42import java.util.ArrayList;
43import java.util.List;
44
45class PrintPreviewController implements MutexFileProvider.OnReleaseRequestCallback,
46        PageAdapter.PreviewArea, EmbeddedContentContainer.OnSizeChangeListener {
47
48    private final PrintActivity mActivity;
49
50    private final MutexFileProvider mFileProvider;
51    private final MyHandler mHandler;
52
53    private final PageAdapter mPageAdapter;
54    private final StaggeredGridLayoutManager mLayoutManger;
55
56    private final PrintOptionsLayout mPrintOptionsLayout;
57    private final RecyclerView mRecyclerView;
58    private final PrintContentView mContentView;
59    private final EmbeddedContentContainer mEmbeddedContentContainer;
60
61    private final PreloadController mPreloadController;
62
63    private int mDocumentPageCount;
64
65    public PrintPreviewController(PrintActivity activity, MutexFileProvider fileProvider) {
66        mActivity = activity;
67        mHandler = new MyHandler(activity.getMainLooper());
68        mFileProvider = fileProvider;
69
70        mPrintOptionsLayout = (PrintOptionsLayout) activity.findViewById(R.id.options_container);
71        mPageAdapter = new PageAdapter(activity, activity, this);
72
73        final int columnCount = mActivity.getResources().getInteger(
74                R.integer.preview_page_per_row_count);
75
76        mLayoutManger = new StaggeredGridLayoutManager(columnCount, OrientationHelper.VERTICAL);
77
78        mRecyclerView = (RecyclerView) activity.findViewById(R.id.preview_content);
79        mRecyclerView.setLayoutManager(mLayoutManger);
80        mRecyclerView.setAdapter(mPageAdapter);
81        mPreloadController = new PreloadController(mRecyclerView);
82        mRecyclerView.setOnScrollListener(mPreloadController);
83
84        mContentView = (PrintContentView) activity.findViewById(R.id.options_content);
85        mEmbeddedContentContainer = (EmbeddedContentContainer) activity.findViewById(
86                R.id.embedded_content_container);
87        mEmbeddedContentContainer.setOnSizeChangeListener(this);
88    }
89
90    @Override
91    public void onSizeChanged(int width, int height) {
92        mPageAdapter.onPreviewAreaSizeChanged();
93    }
94
95    public boolean isOptionsOpened() {
96        return mContentView.isOptionsOpened();
97    }
98
99    public void closeOptions() {
100        mContentView.closeOptions();
101    }
102
103    public void setUiShown(boolean shown) {
104        if (shown) {
105            mRecyclerView.setVisibility(View.VISIBLE);
106        } else {
107            mRecyclerView.setVisibility(View.GONE);
108        }
109    }
110
111    public void onOrientationChanged() {
112        // Adjust the print option column count.
113        final int optionColumnCount = mActivity.getResources().getInteger(
114                R.integer.print_option_column_count);
115        mPrintOptionsLayout.setColumnCount(optionColumnCount);
116        mPageAdapter.onOrientationChanged();
117    }
118
119    public int getFilePageCount() {
120        return mPageAdapter.getFilePageCount();
121    }
122
123    public PageRange[] getSelectedPages() {
124        return mPageAdapter.getSelectedPages();
125    }
126
127    public PageRange[] getRequestedPages() {
128        return mPageAdapter.getRequestedPages();
129    }
130
131    public void onContentUpdated(boolean documentChanged, int documentPageCount,
132            PageRange[] writtenPages, PageRange[] selectedPages, MediaSize mediaSize,
133            Margins minMargins) {
134                boolean contentChanged = false;
135
136        if (documentChanged) {
137            contentChanged = true;
138        }
139
140        if (documentPageCount != mDocumentPageCount) {
141            mDocumentPageCount = documentPageCount;
142            contentChanged = true;
143        }
144
145        if (contentChanged) {
146            // If not closed, close as we start over.
147            if (mPageAdapter.isOpened()) {
148                Message operation = mHandler.obtainMessage(MyHandler.MSG_CLOSE);
149                mHandler.enqueueOperation(operation);
150            }
151        }
152
153        // The content changed. In this case we have to invalidate
154        // all rendered pages and reopen the file...
155        if (contentChanged && writtenPages != null) {
156            Message operation = mHandler.obtainMessage(MyHandler.MSG_OPEN);
157            mHandler.enqueueOperation(operation);
158        }
159
160        // Update the attributes before after closed to avoid flicker.
161        SomeArgs args = SomeArgs.obtain();
162        args.arg1 = writtenPages;
163        args.arg2 = selectedPages;
164        args.arg3 = mediaSize;
165        args.arg4 = minMargins;
166        args.argi1 = documentPageCount;
167
168        Message operation = mHandler.obtainMessage(MyHandler.MSG_UPDATE, args);
169        mHandler.enqueueOperation(operation);
170
171        // If document changed and has pages we want to start preloading.
172        if (contentChanged && writtenPages != null) {
173            operation = mHandler.obtainMessage(MyHandler.MSG_START_PRELOAD);
174            mHandler.enqueueOperation(operation);
175        }
176    }
177
178    @Override
179    public void onReleaseRequested(final File file) {
180        // This is called from the async task's single threaded executor
181        // thread, i.e. not on the main thread - so post a message.
182        mHandler.post(new Runnable() {
183            @Override
184            public void run() {
185                // At this point the other end will write to the file, hence
186                // we have to close it and reopen after the write completes.
187                Message operation = mHandler.obtainMessage(MyHandler.MSG_CLOSE);
188                mHandler.enqueueOperation(operation);
189            }
190        });
191    }
192
193    public void destroy() {
194        if (mPageAdapter.isOpened()) {
195            mPageAdapter.close(null);
196        }
197        mPageAdapter.destroy();
198    }
199
200    @Override
201    public int getWidth() {
202        return mEmbeddedContentContainer.getWidth();
203    }
204
205    @Override
206    public int getHeight() {
207        return mEmbeddedContentContainer.getHeight();
208    }
209
210    @Override
211    public void setColumnCount(int columnCount) {
212        mLayoutManger.setSpanCount(columnCount);
213    }
214
215    @Override
216    public void setPadding(int left, int top , int right, int bottom) {
217        mRecyclerView.setPadding(left, top, right, bottom);
218    }
219
220    private final class MyHandler extends Handler {
221        public static final int MSG_OPEN = 1;
222        public static final int MSG_CLOSE = 2;
223        public static final int MSG_DESTROY = 3;
224        public static final int MSG_UPDATE = 4;
225        public static final int MSG_START_PRELOAD = 5;
226
227        private boolean mAsyncOperationInProgress;
228
229        private final Runnable mOnAsyncOperationDoneCallback = new Runnable() {
230            @Override
231            public void run() {
232                mAsyncOperationInProgress = false;
233                handleNextOperation();
234            }
235        };
236
237        private final List<Message> mPendingOperations = new ArrayList<>();
238
239        public MyHandler(Looper looper) {
240            super(looper, null, false);
241        }
242
243        public void enqueueOperation(Message message) {
244            mPendingOperations.add(message);
245            handleNextOperation();
246        }
247
248        public void handleNextOperation() {
249            while (!mPendingOperations.isEmpty() && !mAsyncOperationInProgress) {
250                Message operation = mPendingOperations.remove(0);
251                handleMessage(operation);
252            }
253        }
254
255        @Override
256        public void handleMessage(Message message) {
257            switch (message.what) {
258                case MSG_OPEN: {
259                    try {
260                        File file = mFileProvider.acquireFile(PrintPreviewController.this);
261                        ParcelFileDescriptor pfd = ParcelFileDescriptor.open(file,
262                                ParcelFileDescriptor.MODE_READ_ONLY);
263
264                        mAsyncOperationInProgress = true;
265                        mPageAdapter.open(pfd, new Runnable() {
266                            @Override
267                            public void run() {
268                                if (mDocumentPageCount == PrintDocumentInfo.PAGE_COUNT_UNKNOWN) {
269                                    mDocumentPageCount = mPageAdapter.getFilePageCount();
270                                    mActivity.updateOptionsUi();
271                                }
272                                mOnAsyncOperationDoneCallback.run();
273                            }
274                        });
275                    } catch (FileNotFoundException fnfe) {
276                        /* ignore - file guaranteed to be there */
277                    }
278                } break;
279
280                case MSG_CLOSE: {
281                    mAsyncOperationInProgress = true;
282                    mPageAdapter.close(new Runnable() {
283                        @Override
284                        public void run() {
285                            mFileProvider.releaseFile();
286                            mOnAsyncOperationDoneCallback.run();
287                        }
288                    });
289                } break;
290
291                case MSG_DESTROY: {
292                    mPageAdapter.destroy();
293                    handleNextOperation();
294                } break;
295
296                case MSG_UPDATE: {
297                    SomeArgs args = (SomeArgs) message.obj;
298                    PageRange[] writtenPages = (PageRange[]) args.arg1;
299                    PageRange[] selectedPages = (PageRange[]) args.arg2;
300                    MediaSize mediaSize = (MediaSize) args.arg3;
301                    Margins margins = (Margins) args.arg4;
302                    final int pageCount = args.argi1;
303                    args.recycle();
304
305                    mPageAdapter.update(writtenPages, selectedPages, pageCount,
306                            mediaSize, margins);
307
308                } break;
309
310                case MSG_START_PRELOAD: {
311                    mPreloadController.startPreloadContent();
312                } break;
313            }
314        }
315    }
316
317    private final class PreloadController extends RecyclerView.OnScrollListener {
318        private final RecyclerView mRecyclerView;
319
320        private int mOldScrollState;
321
322        public PreloadController(RecyclerView recyclerView) {
323            mRecyclerView = recyclerView;
324            mOldScrollState = mRecyclerView.getScrollState();
325        }
326
327        @Override
328        public void onScrollStateChanged(RecyclerView recyclerView, int state) {
329            switch (mOldScrollState) {
330                case RecyclerView.SCROLL_STATE_SETTLING: {
331                    if (state == RecyclerView.SCROLL_STATE_IDLE
332                            || state == RecyclerView.SCROLL_STATE_DRAGGING){
333                        startPreloadContent();
334                    }
335                } break;
336
337                case RecyclerView.SCROLL_STATE_IDLE:
338                case RecyclerView.SCROLL_STATE_DRAGGING: {
339                    if (state == RecyclerView.SCROLL_STATE_SETTLING) {
340                        stopPreloadContent();
341                    }
342                } break;
343            }
344            mOldScrollState = state;
345        }
346
347        public void startPreloadContent() {
348            PageAdapter pageAdapter = (PageAdapter) mRecyclerView.getAdapter();
349
350            if (pageAdapter.isOpened()) {
351                PageRange shownPages = computeShownPages();
352                if (shownPages != null) {
353                    pageAdapter.startPreloadContent(shownPages);
354                }
355            }
356        }
357
358        public void stopPreloadContent() {
359            PageAdapter pageAdapter = (PageAdapter) mRecyclerView.getAdapter();
360
361            if (pageAdapter.isOpened()) {
362                pageAdapter.stopPreloadContent();
363            }
364        }
365
366        private PageRange computeShownPages() {
367            final int childCount = mRecyclerView.getChildCount();
368            if (childCount > 0) {
369                LayoutManager layoutManager = mRecyclerView.getLayoutManager();
370
371                View firstChild = layoutManager.getChildAt(0);
372                ViewHolder firstHolder = mRecyclerView.getChildViewHolder(firstChild);
373
374                View lastChild = layoutManager.getChildAt(layoutManager.getChildCount() - 1);
375                ViewHolder lastHolder = mRecyclerView.getChildViewHolder(lastChild);
376
377                return new PageRange(firstHolder.getPosition(), lastHolder.getPosition());
378            }
379            return null;
380        }
381    }
382}
383