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

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/*
 * 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 org.jetbrains.annotations.NotNull;

import java.awt.*;
import java.awt.font.FontRenderContext;
import java.awt.font.GlyphVector;
import java.awt.geom.Point2D;

/**
 * Fragment of text using a common font
 */
class TextFragment implements LineFragment {
  // glyph location that should definitely be outside of painted region
  private static final Point NOWHERE = new Point(1000000000, 1000000000);
  
  @NotNull
  private final GlyphVector myGlyphVector;
  @NotNull
  private final float[] myCharPositions; // i-th value is the x coordinate of right edge of i-th character (counted in visual order)
  
  TextFragment(@NotNull char[] lineChars, int start, int end, boolean isRtl, 
               @NotNull Font font, @NotNull FontRenderContext fontRenderContext) {
    assert start >= 0;
    assert end <= lineChars.length;
    assert start < end;
    myGlyphVector = FontLayoutService.getInstance().layoutGlyphVector(font, fontRenderContext, lineChars, start, end, isRtl);
    int charCount = end - start;
    myCharPositions = new float[charCount]; 
    int charIndex = 0;
    int numGlyphs = myGlyphVector.getNumGlyphs();
    for (int i = 0; i <= numGlyphs; i++) {
      int newCharIndex = i == numGlyphs ? charCount : 
                         isRtl ? (charCount - 1 - myGlyphVector.getGlyphCharIndex(i)) : myGlyphVector.getGlyphCharIndex(i);
      if (newCharIndex > charIndex) {
        float x = (float)myGlyphVector.getGlyphPosition(i).getX();
        for (int j = charIndex; j < newCharIndex; j++) {
          myCharPositions[j] = x;
        }
        charIndex = newCharIndex;
      }
    }
  }

  @Override
  public int getLength() {
    return myCharPositions.length;
  }

  @Override
  public int getLogicalColumnCount(int startColumn) {
    return myCharPositions.length;
  }

  @Override
  public int getVisualColumnCount(float startX) {
    return myCharPositions.length;
  }

  @Override
  public void draw(Graphics2D g, float x, float y, int startColumn, int endColumn) {
    assert startColumn >= 0; 
    assert endColumn <= myCharPositions.length;
    assert startColumn < endColumn;
    if (startColumn == 0 && endColumn == myCharPositions.length) {
      g.drawGlyphVector(myGlyphVector, x, y);
    }
    else {
      // We cannot use our own GlyphVector implementation, as it wouldn't support
      // Mac-specific automatic font fallback (negative glyph indices will be rejected,
      // even though they are used inside StandardGlyphVector in that case).
      // We also cannot clone myGlyphVector without casting to sun.font.StandardGlyphVector, 
      // as clone() method is not public in GlyphVector (even though it's Cloneable).
      // So we are modifying glyph positions in-place, and restore them after painting.
      int logicalStartOffset = isRtl() ? myCharPositions.length - endColumn : startColumn;
      int logicalEndOffset = isRtl() ? myCharPositions.length - startColumn : endColumn;
      int glyphCount = myGlyphVector.getNumGlyphs();
      Point2D[] savedPositions = new Point2D[glyphCount + 1];
      int lastPaintedGlyph = -1;
      for (int i = 0; i < glyphCount; i++) {
        savedPositions[i] = myGlyphVector.getGlyphPosition(i);
        int c = myGlyphVector.getGlyphCharIndex(i);
        if (c >= logicalStartOffset && c < logicalEndOffset) {
          lastPaintedGlyph = i;
        }
        else {
          myGlyphVector.setGlyphPosition(i, NOWHERE);
        }
      }
      savedPositions[glyphCount] = myGlyphVector.getGlyphPosition(glyphCount);
      myGlyphVector.setGlyphPosition(glyphCount, savedPositions[lastPaintedGlyph + 1]);
      try {
        g.drawGlyphVector(myGlyphVector, x - getX(startColumn), y);
      }
      finally {
        for (int i = 0; i <= glyphCount; i++) {
          myGlyphVector.setGlyphPosition(i, savedPositions[i]);
        }
      }
    }
  }
  
  private boolean isRtl() {
    return (myGlyphVector.getLayoutFlags() & GlyphVector.FLAG_RUN_RTL) != 0;
  }

  @NotNull
  @Override
  public LineFragment subFragment(int startOffset, int endOffset) {
    assert startOffset >= 0;
    assert endOffset <= myCharPositions.length;
    assert startOffset < endOffset;
    if (startOffset == 0 && endOffset == myCharPositions.length) return this;
    return new TextFragmentWindow(startOffset, endOffset);
  }

  @Override
  public float offsetToX(float startX, int startOffset, int offset) {
    return startX + getX(offset) - getX(startOffset);
  }
  
  private float getX(int offset) {
    return offset <= 0 ? 0 : myCharPositions[Math.min(myCharPositions.length, offset) - 1];
  }

  @Override
  public int logicalToVisualColumn(float startX, int startColumn, int column) {
    return column;
  }

  @Override
  public int visualToLogicalColumn(float startX, int startColumn, int column) {
    return column;
  }

  @Override
  public int[] xToVisualColumn(float startX, float x) {
    float relX = x - startX;
    float prevPos = 0;
    for (int i = 0; i < myCharPositions.length; i++) {
      float newPos = myCharPositions[i];
      if (relX < (newPos + prevPos) / 2) {
        return new int[] {i, relX <= prevPos ? 0 : 1};
      }
      prevPos = newPos;
    }
    return new int[] {myCharPositions.length, relX <= myCharPositions[myCharPositions.length - 1] ? 0 : 1};
  }

  @Override
  public float visualColumnToX(float startX, int column) {
    return startX + getX(column);
  }

  private class TextFragmentWindow implements LineFragment {
    private final int myStartOffset;
    private final int myEndOffset;

    private TextFragmentWindow(int startOffset, int endOffset) {
      myStartOffset = startOffset;
      myEndOffset = endOffset;
    }

    @Override
    public int getLength() {
      return myEndOffset - myStartOffset;
    }

    @Override
    public int getLogicalColumnCount(int startColumn) {
      return getLength();
    }

    @Override
    public int getVisualColumnCount(float startX) {
      return getLength();
    }

    @Override
    public int logicalToVisualColumn(float startX, int startColumn, int column) {
      return column;
    }

    @Override
    public int visualToLogicalColumn(float startX, int startColumn, int column) {
      return column;
    }

    @Override
    public float offsetToX(float startX, int startOffset, int offset) {
      return TextFragment.this.offsetToX(startX, visualColumnToParent(startOffset), visualColumnToParent(offset));
    }

    @Override
    public float visualColumnToX(float startX, int column) {
      return startX + getX(visualColumnToParent(column)) - getX(visualColumnToParent(0));
    }

    @Override
    public int[] xToVisualColumn(float startX, float x) {
      int startColumnInParent = visualColumnToParent(0);
      float parentStartX = startX - getX(startColumnInParent);
      int[] parentColumn = TextFragment.this.xToVisualColumn(parentStartX, x);
      int column = parentColumn[0] - startColumnInParent;
      int length = getLength();
      return column < 0 ? new int[] {0, 0} : column > length ? new int[] {length, 1} : new int[] {column, parentColumn[1]};
    }

    private int visualColumnToParent(int column) {
      return column + (isRtl() ? myCharPositions.length - myEndOffset : myStartOffset);
    }

    @Override
    public void draw(Graphics2D g, float x, float y, int startColumn, int endColumn) {
      TextFragment.this.draw(g, x, y, visualColumnToParent(startColumn), visualColumnToParent(endColumn));
    }

    @NotNull
    @Override
    public LineFragment subFragment(int startOffset, int endOffset) {
      return new TextFragmentWindow(startOffset + myStartOffset, endOffset + myStartOffset);
    }
  }
}