com.intellij.openapi.editor.impl.view.TextLayoutCache Maven / Gradle / Ivy

Go to download
/*
 * Copyright 2000-2015 JetBrains s.r.o.
 *
 * 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.intellij.openapi.editor.impl.view;

import com.intellij.openapi.Disposable;
import com.intellij.openapi.editor.Document;
import com.intellij.openapi.editor.event.DocumentEvent;
import com.intellij.openapi.editor.ex.PrioritizedDocumentListener;
import com.intellij.openapi.editor.impl.EditorDocumentPriorities;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.ArrayList;
import java.util.Collections;

/**
 * Editor text layout storage. It's cached on a per-line basis, created lazily (when requested), and invalidated on document changes or
 * when explicitly requested.
 */
class TextLayoutCache implements PrioritizedDocumentListener, Disposable {
  private final EditorView myView;
  private final Document myDocument;
  private final ArrayList myLines = new ArrayList();
  private int myDocumentChangeOldEndLine;

  TextLayoutCache(EditorView view) {
    myView = view;
    myDocument = view.getEditor().getDocument();
    myDocument.addDocumentListener(this, this);
  }

  @Override
  public int getPriority() {
    return EditorDocumentPriorities.EDITOR_TEXT_LAYOUT_CACHE;
  }

  @Override
  public void beforeDocumentChange(DocumentEvent event) {
    myDocumentChangeOldEndLine = getAdjustedLineNumber(event.getOffset() + event.getOldLength());
  }

  @Override
  public void documentChanged(DocumentEvent event) {
    int startLine = myDocument.getLineNumber(event.getOffset());
    int newEndLine = getAdjustedLineNumber(event.getOffset() + event.getNewLength());
    invalidateLines(startLine, myDocumentChangeOldEndLine, newEndLine);
  }

  @Override
  public void dispose() {
  }

  private int getAdjustedLineNumber(int offset) {
    return myDocument.getTextLength() == 0 ? -1 : myDocument.getLineNumber(offset);
  }

  void resetToDocumentSize() {
    invalidateLines(0, myLines.size() - 1, myDocument.getLineCount() - 1);
  }
  
  void invalidateLines(int startLine, int oldEndLine, int newEndLine) {
    int endLine = Math.min(oldEndLine, newEndLine);
    for (int line = startLine; line <= endLine; line++) {
      myLines.set(line, null);
    }
    if (oldEndLine < newEndLine) {
      myLines.addAll(oldEndLine + 1, Collections.nCopies(newEndLine - oldEndLine, (LineLayout)null));
    } else if (oldEndLine > newEndLine) {
      myLines.subList(newEndLine + 1, oldEndLine + 1).clear();
    }
  }
  
  @NotNull
  LineLayout getLineLayout(int line) {
    LineLayout result = getCachedLineLayout(line);
    if (result == null) {
      int lineStart = myDocument.getLineStartOffset(line);
      int lineEnd = myDocument.getLineEndOffset(line);
      result = new LineLayout(myView, lineStart, lineEnd, myView.getFontRenderContext());
      myLines.set(line, result);
    }
    return result;
  }
  
  @Nullable
  LineLayout getCachedLineLayout(int line) {
    return myLines.get(line);
  }
}