gecko-dev/gfx/thebes/gfxDWriteTextAnalysis.cpp

258 lines
7.5 KiB
C++

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "gfxDWriteTextAnalysis.h"
TextAnalysis::TextAnalysis(const wchar_t* text,
UINT32 textLength,
const wchar_t* localeName,
DWRITE_READING_DIRECTION readingDirection)
: mText(text)
, mTextLength(textLength)
, mLocaleName(localeName)
, mReadingDirection(readingDirection)
, mCurrentRun(nullptr)
{
}
TextAnalysis::~TextAnalysis()
{
// delete runs, except mRunHead which is part of the TextAnalysis object
for (Run *run = mRunHead.nextRun; run;) {
Run *origRun = run;
run = run->nextRun;
delete origRun;
}
}
STDMETHODIMP
TextAnalysis::GenerateResults(IDWriteTextAnalyzer* textAnalyzer,
OUT Run **runHead)
{
// Analyzes the text using the script analyzer and returns
// the result as a series of runs.
HRESULT hr = S_OK;
// Initially start out with one result that covers the entire range.
// This result will be subdivided by the analysis processes.
mRunHead.mTextStart = 0;
mRunHead.mTextLength = mTextLength;
mRunHead.mBidiLevel =
(mReadingDirection == DWRITE_READING_DIRECTION_RIGHT_TO_LEFT);
mRunHead.nextRun = nullptr;
mCurrentRun = &mRunHead;
// Call each of the analyzers in sequence, recording their results.
if (SUCCEEDED(hr = textAnalyzer->AnalyzeScript(this,
0,
mTextLength,
this))) {
*runHead = &mRunHead;
}
return hr;
}
////////////////////////////////////////////////////////////////////////////////
// IDWriteTextAnalysisSource source implementation
IFACEMETHODIMP
TextAnalysis::GetTextAtPosition(UINT32 textPosition,
OUT WCHAR const** textString,
OUT UINT32* textLength)
{
if (textPosition >= mTextLength) {
// No text at this position, valid query though.
*textString = nullptr;
*textLength = 0;
} else {
*textString = mText + textPosition;
*textLength = mTextLength - textPosition;
}
return S_OK;
}
IFACEMETHODIMP
TextAnalysis::GetTextBeforePosition(UINT32 textPosition,
OUT WCHAR const** textString,
OUT UINT32* textLength)
{
if (textPosition == 0 || textPosition > mTextLength) {
// Either there is no text before here (== 0), or this
// is an invalid position. The query is considered valid thouh.
*textString = nullptr;
*textLength = 0;
} else {
*textString = mText;
*textLength = textPosition;
}
return S_OK;
}
DWRITE_READING_DIRECTION STDMETHODCALLTYPE
TextAnalysis::GetParagraphReadingDirection()
{
// We support only a single reading direction.
return mReadingDirection;
}
IFACEMETHODIMP
TextAnalysis::GetLocaleName(UINT32 textPosition,
OUT UINT32* textLength,
OUT WCHAR const** localeName)
{
// Single locale name is used, valid until the end of the string.
*localeName = mLocaleName;
*textLength = mTextLength - textPosition;
return S_OK;
}
IFACEMETHODIMP
TextAnalysis::GetNumberSubstitution(UINT32 textPosition,
OUT UINT32* textLength,
OUT IDWriteNumberSubstitution** numberSubstitution)
{
// We do not support number substitution.
*numberSubstitution = nullptr;
*textLength = mTextLength - textPosition;
return S_OK;
}
////////////////////////////////////////////////////////////////////////////////
// IDWriteTextAnalysisSink implementation
IFACEMETHODIMP
TextAnalysis::SetLineBreakpoints(UINT32 textPosition,
UINT32 textLength,
DWRITE_LINE_BREAKPOINT const* lineBreakpoints)
{
// We don't use this for now.
return S_OK;
}
IFACEMETHODIMP
TextAnalysis::SetScriptAnalysis(UINT32 textPosition,
UINT32 textLength,
DWRITE_SCRIPT_ANALYSIS const* scriptAnalysis)
{
SetCurrentRun(textPosition);
SplitCurrentRun(textPosition);
while (textLength > 0) {
Run *run = FetchNextRun(&textLength);
run->mScript = *scriptAnalysis;
}
return S_OK;
}
IFACEMETHODIMP
TextAnalysis::SetBidiLevel(UINT32 textPosition,
UINT32 textLength,
UINT8 explicitLevel,
UINT8 resolvedLevel)
{
// We don't use this for now.
return S_OK;
}
IFACEMETHODIMP
TextAnalysis::SetNumberSubstitution(UINT32 textPosition,
UINT32 textLength,
IDWriteNumberSubstitution* numberSubstitution)
{
// We don't use this for now.
return S_OK;
}
////////////////////////////////////////////////////////////////////////////////
// Run modification.
TextAnalysis::Run *
TextAnalysis::FetchNextRun(IN OUT UINT32* textLength)
{
// Used by the sink setters, this returns a reference to the next run.
// Position and length are adjusted to now point after the current run
// being returned.
Run *origRun = mCurrentRun;
// Split the tail if needed (the length remaining is less than the
// current run's size).
if (*textLength < mCurrentRun->mTextLength) {
SplitCurrentRun(mCurrentRun->mTextStart + *textLength);
} else {
// Just advance the current run.
mCurrentRun = mCurrentRun->nextRun;
}
*textLength -= origRun->mTextLength;
// Return a reference to the run that was just current.
return origRun;
}
void TextAnalysis::SetCurrentRun(UINT32 textPosition)
{
// Move the current run to the given position.
// Since the analyzers generally return results in a forward manner,
// this will usually just return early. If not, find the
// corresponding run for the text position.
if (mCurrentRun && mCurrentRun->ContainsTextPosition(textPosition)) {
return;
}
for (Run *run = &mRunHead; run; run = run->nextRun) {
if (run->ContainsTextPosition(textPosition)) {
mCurrentRun = run;
return;
}
}
NS_NOTREACHED("We should always be able to find the text position in one \
of our runs");
}
void TextAnalysis::SplitCurrentRun(UINT32 splitPosition)
{
if (!mCurrentRun) {
NS_ASSERTION(false, "SplitCurrentRun called without current run.");
// Shouldn't be calling this when no current run is set!
return;
}
// Split the current run.
if (splitPosition <= mCurrentRun->mTextStart) {
// No need to split, already the start of a run
// or before it. Usually the first.
return;
}
Run *newRun = new Run;
*newRun = *mCurrentRun;
// Insert the new run in our linked list.
newRun->nextRun = mCurrentRun->nextRun;
mCurrentRun->nextRun = newRun;
// Adjust runs' text positions and lengths.
UINT32 splitPoint = splitPosition - mCurrentRun->mTextStart;
newRun->mTextStart += splitPoint;
newRun->mTextLength -= splitPoint;
mCurrentRun->mTextLength = splitPoint;
mCurrentRun = newRun;
}