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/*
* Copyright (C) 2013 The Android Open Source Project
*
* 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 android.graphics;
import com.android.ide.common.rendering.api.LayoutLog;
import com.android.layoutlib.bridge.Bridge;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.Toolkit;
import java.awt.font.FontRenderContext;
import java.awt.font.GlyphVector;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import com.ibm.icu.lang.UScript;
import com.ibm.icu.lang.UScriptRun;
import com.ibm.icu.text.Bidi;
import com.ibm.icu.text.BidiRun;
import android.graphics.Paint_Delegate.FontInfo;
/**
* Render the text by breaking it into various scripts and using the right font for each script.
* Can be used to measure the text without actually drawing it.
*/
@SuppressWarnings("deprecation")
public class BidiRenderer {
private static class ScriptRun {
int start;
int limit;
boolean isRtl;
int scriptCode;
Font font;
public ScriptRun(int start, int limit, boolean isRtl) {
this.start = start;
this.limit = limit;
this.isRtl = isRtl;
this.scriptCode = UScript.INVALID_CODE;
}
}
private final Graphics2D mGraphics;
private final Paint_Delegate mPaint;
private char[] mText;
// This List can contain nulls. A null font implies that the we weren't able to load the font
// properly. So, if we encounter a situation where we try to use that font, log a warning.
private List<Font> mFonts;
// Bounds of the text drawn so far.
private RectF mBounds;
private float mBaseline;
/**
* @param graphics May be null.
* @param paint The Paint to use to get the fonts. Should not be null.
* @param text Unidirectional text. Should not be null.
*/
public BidiRenderer(Graphics2D graphics, Paint_Delegate paint, char[] text) {
assert (paint != null);
mGraphics = graphics;
mPaint = paint;
mText = text;
mFonts = new ArrayList<Font>(paint.getFonts().size());
for (FontInfo fontInfo : paint.getFonts()) {
if (fontInfo == null) {
mFonts.add(null);
continue;
}
mFonts.add(fontInfo.mFont);
}
mBounds = new RectF();
}
/**
*
* @param x The x-coordinate of the left edge of where the text should be drawn on the given
* graphics.
* @param y The y-coordinate at which to draw the text on the given mGraphics.
*
*/
public BidiRenderer setRenderLocation(float x, float y) {
mBounds = new RectF(x, y, x, y);
mBaseline = y;
return this;
}
/**
* Perform Bidi Analysis on the text and then render it.
* <p/>
* To skip the analysis and render unidirectional text, see {@link
* #renderText(int, int, boolean, float[], int, boolean)}
*/
public RectF renderText(int start, int limit, int bidiFlags, float[] advances,
int advancesIndex, boolean draw) {
Bidi bidi = new Bidi(mText, start, null, 0, limit - start, getIcuFlags(bidiFlags));
for (int i = 0; i < bidi.countRuns(); i++) {
BidiRun visualRun = bidi.getVisualRun(i);
boolean isRtl = visualRun.getDirection() == Bidi.RTL;
renderText(visualRun.getStart(), visualRun.getLimit(), isRtl, advances,
advancesIndex, draw);
}
return mBounds;
}
/**
* Render unidirectional text.
* <p/>
* This method can also be used to measure the width of the text without actually drawing it.
* <p/>
* @param start index of the first character
* @param limit index of the first character that should not be rendered.
* @param isRtl is the text right-to-left
* @param advances If not null, then advances for each character to be rendered are returned
* here.
* @param advancesIndex index into advances from where the advances need to be filled.
* @param draw If true and {@code graphics} is not null, draw the rendered text on the graphics
* at the given co-ordinates
* @return A rectangle specifying the bounds of the text drawn.
*/
public RectF renderText(int start, int limit, boolean isRtl, float[] advances,
int advancesIndex, boolean draw) {
// We break the text into scripts and then select font based on it and then render each of
// the script runs.
for (ScriptRun run : getScriptRuns(mText, start, limit, isRtl, mFonts)) {
int flag = Font.LAYOUT_NO_LIMIT_CONTEXT | Font.LAYOUT_NO_START_CONTEXT;
flag |= isRtl ? Font.LAYOUT_RIGHT_TO_LEFT : Font.LAYOUT_LEFT_TO_RIGHT;
renderScript(run.start, run.limit, run.font, flag, advances, advancesIndex, draw);
advancesIndex += run.limit - run.start;
}
return mBounds;
}
/**
* Render a script run to the right of the bounds passed. Use the preferred font to render as
* much as possible. This also implements a fallback mechanism to render characters that cannot
* be drawn using the preferred font.
*/
private void renderScript(int start, int limit, Font preferredFont, int flag,
float[] advances, int advancesIndex, boolean draw) {
if (mFonts.size() == 0 || preferredFont == null) {
return;
}
while (start < limit) {
boolean foundFont = false;
int canDisplayUpTo = preferredFont.canDisplayUpTo(mText, start, limit);
if (canDisplayUpTo == -1) {
// We can draw all characters in the text.
render(start, limit, preferredFont, flag, advances, advancesIndex, draw);
return;
}
if (canDisplayUpTo > start) {
// We can draw something.
render(start, canDisplayUpTo, preferredFont, flag, advances, advancesIndex, draw);
advancesIndex += canDisplayUpTo - start;
start = canDisplayUpTo;
}
// The current character cannot be drawn with the preferred font. Cycle through all the
// fonts to check which one can draw it.
int charCount = Character.isHighSurrogate(mText[start]) ? 2 : 1;
for (Font font : mFonts) {
if (font == null) {
logFontWarning();
continue;
}
canDisplayUpTo = font.canDisplayUpTo(mText, start, start + charCount);
if (canDisplayUpTo == -1) {
render(start, start+charCount, font, flag, advances, advancesIndex, draw);
start += charCount;
advancesIndex += charCount;
foundFont = true;
break;
}
}
if (!foundFont) {
// No font can display this char. Use the preferred font. The char will most
// probably appear as a box or a blank space. We could, probably, use some
// heuristics and break the character into the base character and diacritics and
// then draw it, but it's probably not worth the effort.
render(start, start + charCount, preferredFont, flag, advances, advancesIndex,
draw);
start += charCount;
advancesIndex += charCount;
}
}
}
private static void logFontWarning() {
Bridge.getLog().fidelityWarning(LayoutLog.TAG_BROKEN,
"Some fonts could not be loaded. The rendering may not be perfect. " +
"Try running the IDE with JRE 7.", null, null);
}
/**
* Renders the text to the right of the bounds with the given font.
* @param font The font to render the text with.
*/
private void render(int start, int limit, Font font, int flag, float[] advances,
int advancesIndex, boolean draw) {
FontRenderContext frc;
if (mGraphics != null) {
frc = mGraphics.getFontRenderContext();
} else {
frc = Toolkit.getDefaultToolkit().getFontMetrics(font).getFontRenderContext();
// Metrics obtained this way don't have anti-aliasing set. So,
// we create a new FontRenderContext with anti-aliasing set.
frc = new FontRenderContext(font.getTransform(), mPaint.isAntiAliased(), frc.usesFractionalMetrics());
}
GlyphVector gv = font.layoutGlyphVector(frc, mText, start, limit, flag);
int ng = gv.getNumGlyphs();
int[] ci = gv.getGlyphCharIndices(0, ng, null);
if (advances != null) {
for (int i = 0; i < ng; i++) {
int adv_idx = advancesIndex + ci[i];
advances[adv_idx] += gv.getGlyphMetrics(i).getAdvanceX();
}
}
if (draw && mGraphics != null) {
mGraphics.drawGlyphVector(gv, mBounds.right, mBaseline);
}
// Update the bounds.
Rectangle2D awtBounds = gv.getLogicalBounds();
RectF bounds = awtRectToAndroidRect(awtBounds, mBounds.right, mBaseline);
// If the width of the bounds is zero, no text had been drawn earlier. Hence, use the
// coordinates from the bounds as an offset.
if (Math.abs(mBounds.right - mBounds.left) == 0) {
mBounds = bounds;
} else {
mBounds.union(bounds);
}
}
// --- Static helper methods ---
private static RectF awtRectToAndroidRect(Rectangle2D awtRec, float offsetX, float offsetY) {
float left = (float) awtRec.getX();
float top = (float) awtRec.getY();
float right = (float) (left + awtRec.getWidth());
float bottom = (float) (top + awtRec.getHeight());
RectF androidRect = new RectF(left, top, right, bottom);
androidRect.offset(offsetX, offsetY);
return androidRect;
}
/* package */ static List<ScriptRun> getScriptRuns(char[] text, int start, int limit,
boolean isRtl, List<Font> fonts) {
LinkedList<ScriptRun> scriptRuns = new LinkedList<ScriptRun>();
int count = limit - start;
UScriptRun uScriptRun = new UScriptRun(text, start, count);
while (uScriptRun.next()) {
int scriptStart = uScriptRun.getScriptStart();
int scriptLimit = uScriptRun.getScriptLimit();
ScriptRun run = new ScriptRun(scriptStart, scriptLimit, isRtl);
run.scriptCode = uScriptRun.getScriptCode();
setScriptFont(text, run, fonts);
scriptRuns.add(run);
}
return scriptRuns;
}
// TODO: Replace this method with one which returns the font based on the scriptCode.
private static void setScriptFont(char[] text, ScriptRun run,
List<Font> fonts) {
for (Font font : fonts) {
if (font == null) {
logFontWarning();
continue;
}
if (font.canDisplayUpTo(text, run.start, run.limit) == -1) {
run.font = font;
return;
}
}
run.font = fonts.get(0);
}
private static int getIcuFlags(int bidiFlag) {
switch (bidiFlag) {
case Paint.BIDI_LTR:
case Paint.BIDI_FORCE_LTR:
return Bidi.DIRECTION_LEFT_TO_RIGHT;
case Paint.BIDI_RTL:
case Paint.BIDI_FORCE_RTL:
return Bidi.DIRECTION_RIGHT_TO_LEFT;
case Paint.BIDI_DEFAULT_LTR:
return Bidi.DIRECTION_DEFAULT_LEFT_TO_RIGHT;
case Paint.BIDI_DEFAULT_RTL:
return Bidi.DIRECTION_DEFAULT_RIGHT_TO_LEFT;
default:
assert false;
return Bidi.DIRECTION_DEFAULT_LEFT_TO_RIGHT;
}
}
}
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