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Implemented Pango text metrics and expanded the drawtext basic page to draw metrics. Works on both Pango and OS X; DirectWrite comes next.

This commit is contained in:
Pietro Gagliardi 2017-01-20 16:36:44 -05:00
parent 6ef6ed8cde
commit 6ccf436206
3 changed files with 241 additions and 8 deletions
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2
darwin/drawtext.m
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@ -246,6 +246,8 @@ void uiDrawText(uiDrawContext *c, uiDrawTextLayout *tl, double x, double y)
}
// TODO document that the width and height of a layout is not necessarily the sum of the widths and heights of its constituent lines; this is definitely untrue on OS X, where lines are placed in such a way that the distance between baselines is always integral
// TODO width doesn't include trailing whitespace...
// TODO figure out how paragraph spacing should play into this
void uiDrawTextLayoutExtents(uiDrawTextLayout *tl, double *width, double *height)
{
*width = tl->size.width;

187
examples/drawtext/basic.c
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@ -30,10 +30,93 @@ static uiAttributedString *attrstr;
#define margins 10
static uiBox *panel;
static uiCheckbox *showExtents;
static uiCheckbox *showLineBounds;
static uiCheckbox *showLineGuides;
// TODO should this be const?
static double strokeDashes[] = { 5, 2 };
// TODO this should be const
static uiDrawStrokeParams strokeParams = {
.Cap = uiDrawLineCapFlat,
.Join = uiDrawLineJoinMiter,
.Thickness = 1,
.MiterLimit = uiDrawDefaultMiterLimit,
.Dashes = strokeDashes,
.NumDashes = 2,
.DashPhase = 0,
};
// TODO should be const?
static uiDrawBrush fillBrushes[4] = {
{
.Type = uiDrawBrushTypeSolid,
.R = 1.0,
.G = 0.0,
.B = 0.0,
.A = 0.5,
},
{
.Type = uiDrawBrushTypeSolid,
.R = 0.0,
.G = 1.0,
.B = 0.0,
.A = 0.5,
},
{
.Type = uiDrawBrushTypeSolid,
.R = 0.0,
.G = 0.0,
.B = 1.0,
.A = 0.5,
},
{
.Type = uiDrawBrushTypeSolid,
.R = 0.0,
.G = 1.0,
.B = 1.0,
.A = 0.5,
},
};
// TODO come up with better colors
static uiDrawBrush strokeBrushes[3] = {
// baseline
{
.Type = uiDrawBrushTypeSolid,
.R = 0.5,
.G = 0.5,
.B = 0.0,
.A = 0.75,
},
// ascent
{
.Type = uiDrawBrushTypeSolid,
.R = 1.0,
.G = 0.0,
.B = 1.0,
.A = 0.75,
},
// descent
{
.Type = uiDrawBrushTypeSolid,
.R = 0.5,
.G = 0.75,
.B = 1.0,
.A = 0.75,
},
};
static void draw(uiAreaDrawParams *p)
{
uiDrawPath *path;
uiDrawTextLayout *layout;
uiDrawBrush b;
b.Type = uiDrawBrushTypeSolid;
// only clip the text, not the guides
uiDrawSave(p->Context);
path = uiDrawNewPath(uiDrawFillModeWinding);
uiDrawPathAddRectangle(path, margins, margins,
@ -44,33 +127,131 @@ static void draw(uiAreaDrawParams *p)
uiDrawFreePath(path);
// TODO get rid of this later
#if 0
path = uiDrawNewPath(uiDrawFillModeWinding);
uiDrawPathAddRectangle(path, -100, -100,
p->AreaWidth * 2,
p->AreaHeight * 2);
uiDrawPathEnd(path);
uiDrawBrush b;
b.Type = uiDrawBrushTypeSolid;
b.R = 0.0;
b.G = 1.0;
b.B = 0.0;
b.A = 1.0;
uiDrawFill(p->Context, path, &b);
uiDrawFreePath(path);
#endif
layout = uiDrawNewTextLayout(attrstr,
&defaultFont,
p->AreaWidth - 2 * margins);
uiDrawText(p->Context, layout, margins, margins);
uiDrawRestore(p->Context);
if (uiCheckboxChecked(showExtents)) {
double width, height;
uiDrawTextLayoutExtents(layout, &width, &height);
path = uiDrawNewPath(uiDrawFillModeWinding);
uiDrawPathAddRectangle(path, margins, margins,
width, height);
uiDrawPathEnd(path);
b.R = 1.0;
b.G = 0.0;
b.B = 1.0;
b.A = 0.5;
uiDrawStroke(p->Context, path, &b, &strokeParams);
uiDrawFreePath(path);
}
if (uiCheckboxChecked(showLineBounds) || uiCheckboxChecked(showLineGuides)) {
uiDrawTextLayoutLineMetrics m;
int i, n;
int fill = 0;
n = uiDrawTextLayoutNumLines(layout);
for (i = 0; i < n; i++) {
uiDrawTextLayoutLineGetMetrics(layout, i, &m);
if (uiCheckboxChecked(showLineBounds)) {
path = uiDrawNewPath(uiDrawFillModeWinding);
uiDrawPathAddRectangle(path, margins + m.X, margins + m.Y,
m.Width, m.Height);
uiDrawPathEnd(path);
uiDrawFill(p->Context, path, fillBrushes + fill);
uiDrawFreePath(path);
fill = (fill + 1) % 4;
}
if (uiCheckboxChecked(showLineGuides)) {
// baseline
path = uiDrawNewPath(uiDrawFillModeWinding);
uiDrawPathNewFigure(path,
margins + m.X,
margins + m.BaselineY);
uiDrawPathLineTo(path,
margins + m.X + m.Width,
margins + m.BaselineY);
uiDrawPathEnd(path);
uiDrawStroke(p->Context, path, &(strokeBrushes[0]), &strokeParams);
uiDrawFreePath(path);
// ascent line
path = uiDrawNewPath(uiDrawFillModeWinding);
uiDrawPathNewFigure(path,
margins + m.X,
margins + m.BaselineY - m.Ascent);
uiDrawPathLineTo(path,
margins + m.X + m.Width,
margins + m.BaselineY - m.Ascent);
uiDrawPathEnd(path);
uiDrawStroke(p->Context, path, &(strokeBrushes[1]), &strokeParams);
uiDrawFreePath(path);
// descent line
path = uiDrawNewPath(uiDrawFillModeWinding);
uiDrawPathNewFigure(path,
margins + m.X,
margins + m.BaselineY + m.Descent);
uiDrawPathLineTo(path,
margins + m.X + m.Width,
margins + m.BaselineY + m.Descent);
uiDrawPathEnd(path);
uiDrawStroke(p->Context, path, &(strokeBrushes[2]), &strokeParams);
uiDrawFreePath(path);
}
}
}
uiDrawFreeTextLayout(layout);
}
static struct example basicExample;
// TODO share?
static void checkboxChecked(uiCheckbox *c, void *data)
{
redraw();
}
static uiCheckbox *newCheckbox(const char *text)
{
uiCheckbox *c;
c = uiNewCheckbox(text);
uiCheckboxOnToggled(c, checkboxChecked, NULL);
uiBoxAppend(panel, uiControl(c), 0);
return c;
}
struct example *mkBasicExample(void)
{
panel = uiNewVerticalBox();
showExtents = newCheckbox("Show Layout Extents");
showLineBounds = newCheckbox("Show Line Bounds");
showLineGuides = newCheckbox("Show Line Guides");
basicExample.name = "Basic Paragraph of Text";
basicExample.panel = uiControl(uiNewVerticalBox());
basicExample.panel = uiControl(panel);
basicExample.draw = draw;
attrstr = uiNewAttributedString(text);

60
unix/drawtext.c
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@ -4,6 +4,7 @@
struct uiDrawTextLayout {
PangoLayout *layout;
uiDrawTextLayoutLineMetrics *lineMetrics;
};
// See https://developer.gnome.org/pango/1.30/pango-Cairo-Rendering.html#pango-Cairo-Rendering.description
@ -35,6 +36,55 @@ static const PangoStretch pangoStretches[] = {
[uiDrawTextStretchUltraExpanded] = PANGO_STRETCH_ULTRA_EXPANDED,
};
// TODO neither these nor the overall extents seem to include trailing whitespace... we need to figure that out too
static void computeLineMetrics(uiDrawTextLayout *tl)
{
PangoLayoutIter *iter;
PangoLayoutLine *pll;
PangoRectangle lineStartPos, lineExtents;
int i, n;
uiDrawTextLayoutLineMetrics *m;
n = pango_layout_get_line_count(tl->layout);
tl->lineMetrics = (uiDrawTextLayoutLineMetrics *) uiAlloc(n * sizeof (uiDrawTextLayoutLineMetrics), "uiDrawTextLayoutLineMetrics[] (text layout)");
iter = pango_layout_get_iter(tl->layout);
m = tl->lineMetrics;
for (i = 0; i < n; i++) {
int baselineY;
// TODO we use this instead of _get_yrange() because of the block of text in that function's description about how line spacing is distributed in Pango; we have to worry about this when we start adding line spacing...
baselineY = pango_layout_iter_get_baseline(iter);
pll = pango_layout_iter_get_line_readonly(iter);
pango_layout_index_to_pos(tl->layout, pll->start_index, &lineStartPos);
pango_layout_line_get_extents(pll, NULL, &lineExtents);
// TODO unref pll?
// TODO is this correct for RTL glyphs?
m->X = pangoToCairo(lineStartPos.x);
// TODO fix the whole combined not being updated shenanigans in the static build (here because ugh)
m->Y = pangoToCairo(baselineY - PANGO_ASCENT(lineExtents));
m->Width = pangoToCairo(lineExtents.width);
m->Height = pangoToCairo(lineExtents.height);
m->BaselineY = pangoToCairo(baselineY);
m->Ascent = pangoToCairo(PANGO_ASCENT(lineExtents));
m->Descent = pangoToCairo(PANGO_DESCENT(lineExtents));
m->Leading = 0; // TODO
m->ParagraphSpacingBefore = 0; // TODO
m->LineHeightSpace = 0; // TODO
m->LineSpacing = 0; // TODO
m->ParagraphSpacing = 0; // TODO
// don't worry about the return value; we're not using this after the last line
pango_layout_iter_next_line(iter);
m++;
}
pango_layout_iter_free(iter);
}
uiDrawTextLayout *uiDrawNewTextLayout(uiAttributedString *s, uiDrawFontDescriptor *defaultFont, double width)
{
uiDrawTextLayout *tl;
@ -76,11 +126,14 @@ uiDrawTextLayout *uiDrawNewTextLayout(uiAttributedString *s, uiDrawFontDescripto
// TODO attributes
computeLineMetrics(tl);
return tl;
}
void uiDrawFreeTextLayout(uiDrawTextLayout *tl)
{
uiFree(tl->lineMetrics);
g_object_unref(tl->layout);
uiFree(tl);
}
@ -112,15 +165,12 @@ void uiDrawTextLayoutLineByteRange(uiDrawTextLayout *tl, int line, size_t *start
pll = pango_layout_get_line_readonly(tl->layout, line);
*start = pll->start_index;
*end = pll->start_index + pll->length;
// TODO unref?
// TODO unref pll?
}
void uiDrawTextLayoutLineGetMetrics(uiDrawTextLayout *tl, int line, uiDrawTextLayoutLineMetrics *m)
{
PangoLayoutLine *pll;
pll = pango_layout_get_line_readonly(tl->layout, line);
// TODO unref?
*m = tl->lineMetrics[line];
}
// TODO