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LibGfx: Make text painting better at aligning vector fonts vertically

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This is achieved by simplifying the logic in TextLayout. We get rid
of all the various ways that the layout bounding rect can get cropped.
Then we make sure to use the right pixel metrics.

Finally we use the font's own line gap metrics instead of hard-coding 4.

The end result is that text painted with vector fonts now gets pretty
reasonable vertical alignment in most cases.
This commit is contained in:
Andreas Kling 2023-01-06 11:55:23 +01:00
parent f5e18dda2b
commit b2d3ceaec5
4 changed files with 22 additions and 58 deletions
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48
Userland/Libraries/LibGfx/TextLayout.cpp
View file

@ -20,15 +20,15 @@ struct Block {
Utf8View characters;
};
FloatRect TextLayout::bounding_rect(TextWrapping wrapping, int line_spacing) const
FloatRect TextLayout::bounding_rect(TextWrapping wrapping) const
{
auto lines = wrap_lines(TextElision::None, wrapping, line_spacing, FitWithinRect::No);
if (!lines.size()) {
auto lines = wrap_lines(TextElision::None, wrapping);
if (lines.is_empty()) {
return {};
}
FloatRect bounding_rect = {
0, 0, 0, (lines.size() * (m_font.pixel_size() + line_spacing)) - line_spacing
0, 0, 0, (static_cast<float>(lines.size()) * (m_font_metrics.ascent + m_font_metrics.descent + m_font_metrics.line_gap)) - m_font_metrics.line_gap
};
for (auto& line : lines) {
@ -40,7 +40,7 @@ FloatRect TextLayout::bounding_rect(TextWrapping wrapping, int line_spacing) con
return bounding_rect;
}
Vector<DeprecatedString, 32> TextLayout::wrap_lines(TextElision elision, TextWrapping wrapping, int line_spacing, FitWithinRect fit_within_rect) const
Vector<DeprecatedString, 32> TextLayout::wrap_lines(TextElision elision, TextWrapping wrapping) const
{
Vector<Block> blocks;
@ -106,34 +106,16 @@ Vector<DeprecatedString, 32> TextLayout::wrap_lines(TextElision elision, TextWra
});
}
size_t max_lines_that_can_fit = 0;
if (m_rect.height() >= m_font.glyph_height()) {
// NOTE: If glyph height is 10 and line spacing is 1, we can fit a
// single line into a 10px rect and a 20px rect, but 2 lines into a
// 21px rect.
max_lines_that_can_fit = 1 + (m_rect.height() - m_font.glyph_height()) / (m_font.glyph_height() + line_spacing);
}
if (max_lines_that_can_fit == 0)
return {};
Vector<DeprecatedString> lines;
StringBuilder builder;
float line_width = 0;
size_t current_block = 0;
bool did_not_finish = false;
for (Block& block : blocks) {
switch (block.type) {
case BlockType::Newline: {
lines.append(builder.to_deprecated_string());
builder.clear();
line_width = 0;
if (lines.size() == max_lines_that_can_fit && fit_within_rect == FitWithinRect::Yes) {
did_not_finish = true;
goto blocks_processed;
}
current_block++;
continue;
}
@ -152,11 +134,6 @@ Vector<DeprecatedString, 32> TextLayout::wrap_lines(TextElision elision, TextWra
line_width = 0;
}
if (lines.size() == max_lines_that_can_fit && fit_within_rect == FitWithinRect::Yes) {
did_not_finish = true;
goto blocks_processed;
}
builder.append(block.characters.as_string());
line_width += block_width;
current_block++;
@ -164,18 +141,15 @@ Vector<DeprecatedString, 32> TextLayout::wrap_lines(TextElision elision, TextWra
}
}
blocks_processed:
if (!did_not_finish) {
auto last_line = builder.to_deprecated_string();
if (!last_line.is_empty())
lines.append(last_line);
}
auto last_line = builder.to_deprecated_string();
if (!last_line.is_empty())
lines.append(last_line);
switch (elision) {
case TextElision::None:
break;
case TextElision::Right: {
lines.at(lines.size() - 1) = elide_text_from_right(Utf8View { lines.at(lines.size() - 1) }, did_not_finish);
lines.at(lines.size() - 1) = elide_text_from_right(Utf8View { lines.at(lines.size() - 1) });
break;
}
}
@ -183,10 +157,10 @@ blocks_processed:
return lines;
}
DeprecatedString TextLayout::elide_text_from_right(Utf8View text, bool force_elision) const
DeprecatedString TextLayout::elide_text_from_right(Utf8View text) const
{
float text_width = m_font.width(text);
if (force_elision || text_width > static_cast<unsigned>(m_rect.width())) {
if (text_width > static_cast<float>(m_rect.width())) {
float ellipsis_width = m_font.width("..."sv);
float current_width = ellipsis_width;
size_t glyph_spacing = m_font.glyph_spacing();