michael@0: /*
michael@0:  * Copyright 2006 The Android Open Source Project
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #include "SkTextBox.h"
michael@0: #include "SkUtils.h"
michael@0: 
michael@0: static inline int is_ws(int c)
michael@0: {
michael@0:     return !((c - 1) >> 5);
michael@0: }
michael@0: 
michael@0: static size_t linebreak(const char text[], const char stop[],
michael@0:                         const SkPaint& paint, SkScalar margin,
michael@0:                         size_t* trailing = NULL)
michael@0: {
michael@0:     size_t lengthBreak = paint.breakText(text, stop - text, margin);
michael@0: 
michael@0:     //Check for white space or line breakers before the lengthBreak
michael@0:     const char* start = text;
michael@0:     const char* word_start = text;
michael@0:     int prevWS = true;
michael@0:     if (trailing) {
michael@0:         *trailing = 0;
michael@0:     }
michael@0: 
michael@0:     while (text < stop) {
michael@0:         const char* prevText = text;
michael@0:         SkUnichar uni = SkUTF8_NextUnichar(&text);
michael@0:         int currWS = is_ws(uni);
michael@0: 
michael@0:         if (!currWS && prevWS) {
michael@0:             word_start = prevText;
michael@0:         }
michael@0:         prevWS = currWS;
michael@0: 
michael@0:         if (text > start + lengthBreak) {
michael@0:             if (currWS) {
michael@0:                 // eat the rest of the whitespace
michael@0:                 while (text < stop && is_ws(SkUTF8_ToUnichar(text))) {
michael@0:                     text += SkUTF8_CountUTF8Bytes(text);
michael@0:                 }
michael@0:                 if (trailing) {
michael@0:                     *trailing = text - prevText;
michael@0:                 }
michael@0:             } else {
michael@0:                 // backup until a whitespace (or 1 char)
michael@0:                 if (word_start == start) {
michael@0:                     if (prevText > start) {
michael@0:                         text = prevText;
michael@0:                     }
michael@0:                 } else {
michael@0:                     text = word_start;
michael@0:                 }
michael@0:             }
michael@0:             break;
michael@0:         }
michael@0: 
michael@0:         if ('\n' == uni) {
michael@0:             size_t ret = text - start;
michael@0:             size_t lineBreakSize = 1;
michael@0:             if (text < stop) {
michael@0:                 uni = SkUTF8_NextUnichar(&text);
michael@0:                 if ('\r' == uni) {
michael@0:                     ret = text - start;
michael@0:                     ++lineBreakSize;
michael@0:                 }
michael@0:             }
michael@0:             if (trailing) {
michael@0:                 *trailing = lineBreakSize;
michael@0:             }
michael@0:             return ret;
michael@0:         }
michael@0: 
michael@0:         if ('\r' == uni) {
michael@0:             size_t ret = text - start;
michael@0:             size_t lineBreakSize = 1;
michael@0:             if (text < stop) {
michael@0:                 uni = SkUTF8_NextUnichar(&text);
michael@0:                 if ('\n' == uni) {
michael@0:                     ret = text - start;
michael@0:                     ++lineBreakSize;
michael@0:                 }
michael@0:             }
michael@0:             if (trailing) {
michael@0:                 *trailing = lineBreakSize;
michael@0:             }
michael@0:             return ret;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     return text - start;
michael@0: }
michael@0: 
michael@0: int SkTextLineBreaker::CountLines(const char text[], size_t len, const SkPaint& paint, SkScalar width)
michael@0: {
michael@0:     const char* stop = text + len;
michael@0:     int         count = 0;
michael@0: 
michael@0:     if (width > 0)
michael@0:     {
michael@0:         do {
michael@0:             count += 1;
michael@0:             text += linebreak(text, stop, paint, width);
michael@0:         } while (text < stop);
michael@0:     }
michael@0:     return count;
michael@0: }
michael@0: 
michael@0: //////////////////////////////////////////////////////////////////////////////
michael@0: 
michael@0: SkTextBox::SkTextBox()
michael@0: {
michael@0:     fBox.setEmpty();
michael@0:     fSpacingMul = SK_Scalar1;
michael@0:     fSpacingAdd = 0;
michael@0:     fMode = kLineBreak_Mode;
michael@0:     fSpacingAlign = kStart_SpacingAlign;
michael@0: }
michael@0: 
michael@0: void SkTextBox::setMode(Mode mode)
michael@0: {
michael@0:     SkASSERT((unsigned)mode < kModeCount);
michael@0:     fMode = SkToU8(mode);
michael@0: }
michael@0: 
michael@0: void SkTextBox::setSpacingAlign(SpacingAlign align)
michael@0: {
michael@0:     SkASSERT((unsigned)align < kSpacingAlignCount);
michael@0:     fSpacingAlign = SkToU8(align);
michael@0: }
michael@0: 
michael@0: void SkTextBox::getBox(SkRect* box) const
michael@0: {
michael@0:     if (box)
michael@0:         *box = fBox;
michael@0: }
michael@0: 
michael@0: void SkTextBox::setBox(const SkRect& box)
michael@0: {
michael@0:     fBox = box;
michael@0: }
michael@0: 
michael@0: void SkTextBox::setBox(SkScalar left, SkScalar top, SkScalar right, SkScalar bottom)
michael@0: {
michael@0:     fBox.set(left, top, right, bottom);
michael@0: }
michael@0: 
michael@0: void SkTextBox::getSpacing(SkScalar* mul, SkScalar* add) const
michael@0: {
michael@0:     if (mul)
michael@0:         *mul = fSpacingMul;
michael@0:     if (add)
michael@0:         *add = fSpacingAdd;
michael@0: }
michael@0: 
michael@0: void SkTextBox::setSpacing(SkScalar mul, SkScalar add)
michael@0: {
michael@0:     fSpacingMul = mul;
michael@0:     fSpacingAdd = add;
michael@0: }
michael@0: 
michael@0: /////////////////////////////////////////////////////////////////////////////////////////////
michael@0: 
michael@0: void SkTextBox::draw(SkCanvas* canvas, const char text[], size_t len, const SkPaint& paint)
michael@0: {
michael@0:     SkASSERT(canvas && &paint && (text || len == 0));
michael@0: 
michael@0:     SkScalar marginWidth = fBox.width();
michael@0: 
michael@0:     if (marginWidth <= 0 || len == 0)
michael@0:         return;
michael@0: 
michael@0:     const char* textStop = text + len;
michael@0: 
michael@0:     SkScalar                x, y, scaledSpacing, height, fontHeight;
michael@0:     SkPaint::FontMetrics    metrics;
michael@0: 
michael@0:     switch (paint.getTextAlign()) {
michael@0:     case SkPaint::kLeft_Align:
michael@0:         x = 0;
michael@0:         break;
michael@0:     case SkPaint::kCenter_Align:
michael@0:         x = SkScalarHalf(marginWidth);
michael@0:         break;
michael@0:     default:
michael@0:         x = marginWidth;
michael@0:         break;
michael@0:     }
michael@0:     x += fBox.fLeft;
michael@0: 
michael@0:     fontHeight = paint.getFontMetrics(&metrics);
michael@0:     scaledSpacing = SkScalarMul(fontHeight, fSpacingMul) + fSpacingAdd;
michael@0:     height = fBox.height();
michael@0: 
michael@0:     //  compute Y position for first line
michael@0:     {
michael@0:         SkScalar textHeight = fontHeight;
michael@0: 
michael@0:         if (fMode == kLineBreak_Mode && fSpacingAlign != kStart_SpacingAlign)
michael@0:         {
michael@0:             int count = SkTextLineBreaker::CountLines(text, textStop - text, paint, marginWidth);
michael@0:             SkASSERT(count > 0);
michael@0:             textHeight += scaledSpacing * (count - 1);
michael@0:         }
michael@0: 
michael@0:         switch (fSpacingAlign) {
michael@0:         case kStart_SpacingAlign:
michael@0:             y = 0;
michael@0:             break;
michael@0:         case kCenter_SpacingAlign:
michael@0:             y = SkScalarHalf(height - textHeight);
michael@0:             break;
michael@0:         default:
michael@0:             SkASSERT(fSpacingAlign == kEnd_SpacingAlign);
michael@0:             y = height - textHeight;
michael@0:             break;
michael@0:         }
michael@0:         y += fBox.fTop - metrics.fAscent;
michael@0:     }
michael@0: 
michael@0:     for (;;)
michael@0:     {
michael@0:         size_t trailing;
michael@0:         len = linebreak(text, textStop, paint, marginWidth, &trailing);
michael@0:         if (y + metrics.fDescent + metrics.fLeading > 0)
michael@0:             canvas->drawText(text, len - trailing, x, y, paint);
michael@0:         text += len;
michael@0:         if (text >= textStop)
michael@0:             break;
michael@0:         y += scaledSpacing;
michael@0:         if (y + metrics.fAscent >= fBox.fBottom)
michael@0:             break;
michael@0:     }
michael@0: }
michael@0: 
michael@0: ///////////////////////////////////////////////////////////////////////////////
michael@0: 
michael@0: void SkTextBox::setText(const char text[], size_t len, const SkPaint& paint) {
michael@0:     fText = text;
michael@0:     fLen = len;
michael@0:     fPaint = &paint;
michael@0: }
michael@0: 
michael@0: void SkTextBox::draw(SkCanvas* canvas) {
michael@0:     this->draw(canvas, fText, fLen, *fPaint);
michael@0: }
michael@0: 
michael@0: int SkTextBox::countLines() const {
michael@0:     return SkTextLineBreaker::CountLines(fText, fLen, *fPaint, fBox.width());
michael@0: }
michael@0: 
michael@0: SkScalar SkTextBox::getTextHeight() const {
michael@0:     SkScalar spacing = SkScalarMul(fPaint->getTextSize(), fSpacingMul) + fSpacingAdd;
michael@0:     return this->countLines() * spacing;
michael@0: }