Wrote the text drawing code on Windows. Now to build and test.

darwin/draw.m

@@ -509,6 +509,7 @@ struct uiDrawTextLayout {
 };
 
 // TODO this is *really* iffy, but we need to know character offsets...
+// TODO clean up the local variable names and improve documentation
 static intmax_t *strToCFStrOffsetList(const char *str, CFMutableStringRef *cfstr)
 {
 	intmax_t *bytesToCharacters;
@@ -768,6 +769,7 @@ void uiDrawFreeTextLayout(uiDrawTextLayout *layout)
 
 // Core Text doesn't draw onto a flipped view correctly; we have to do this
 // see the iOS bits of the first example at https://developer.apple.com/library/mac/documentation/StringsTextFonts/Conceptual/CoreText_Programming/LayoutOperations/LayoutOperations.html#//apple_ref/doc/uid/TP40005533-CH12-SW1 (iOS is naturally flipped)
+// TODO how is this affected by the CTM?
 static void prepareContextForText(uiDrawContext *c, double *y)
 {
 	CGContextSaveGState(c->c);

windows/draw.c

@@ -873,3 +873,20 @@ void uiDrawRestore(uiDrawContext *c)
 	uiFree(state);
 	ptrArrayDelete(c->states, c->states->len - 1);
 }
+
+// TODO document that fully opaque black is the default text color; figure out whether this is upheld in various scenarios on other platforms
+void uiDrawText(uiDrawContext *c, doule x, double y, uiDrawTextLayout *layout)
+{
+	uiDrawBrush brush;
+	ID2D1Brush *black;
+
+	ZeroMemory(&brush, sizeof (uiDrawBrush));
+	brush.Type = uiDrawBrushTypeSolid;
+	brush.R = 0.0;
+	brush.G = 0.0;
+	brush.B = 0.0;
+	brush.A = 1.0;
+	black = makeBrush(&brush, c->rt);
+	doDrawText(c->rt, black, x, y, layout);
+	ID2D1Brush_Release(black);
+}

windows/drawtext.cpp

@@ -120,7 +120,152 @@ double uiDrawPointsToTextSize(double points)
 	return 0;
 }
 
-void uiDrawText(uiDrawContext *c, double x, double y, const char *text, uiDrawTextStyle *style)
+struct uiDrawTextLayout {
+	IDWriteTextFormat *format;
+	IDWriteTextLayout *layout;
+	intmax_t *bytesToCharacters;
+};
+
+#define MBTWC(str, n, wstr, bufsiz) MultiByteToWideChar(CP_UTF8, 0, str, n, wstr, bufsiz)
+
+// TODO figure out how ranges are specified in DirectWrite
+// TODO clean up the local variable names and improve documentation
+static intmax_t *toUTF16Offsets(const char *str, WCHAR **wstr, intmax_t *wlenout)
 {
-	// TODO
+	intmax_t *bytesToCharacters;
+	intmax_t i, len;
+	int wlen;
+	intmax_t outpos;
+
+	len = strlen(str);
+	bytesToCharacters = (intmax_t *) uiAlloc(len * sizeof (intmax_t), "intmax_t[]");
+
+	wlen = MBTWC(str, -1, NULL, 0);
+	if (wlen == 0)
+		logLastError("error figuring out number of characters to convert to in toUTF16Offsets()");
+	*wstr = (WCHAR *) uiAlloc(wlen * sizeof (WCHAR), "WCHAR[]");
+	*wlenout = wlen;
+
+	i = 0;
+	outpos = 0;
+	while (i < len) {
+		intmax_t n;
+		intmax_t j;
+		BOOL found;
+
+		// figure out how many characters to convert and convert them
+		found = FALSE;
+		for (n = 1; (i + n - 1) < len; n++)
+			if (MBTWC(str + i, n, *wstr + outpos, wlen - outpos) == n) {
+				// found a full character
+				found = TRUE;
+				break;
+			}
+		// if this test passes we reached the end of the string without a successful conversion (invalid string)
+		if (!found)
+			logLastError("something bad happened when trying to prepare string in uiDrawNewTextLayout()");
+
+		// now save the character offsets for those bytes
+		for (j = 0; j < n; j++)
+			bytesToCharacters[j] = outpos;
+
+		// and go to the next
+		outpos += n;
+	}
+
+	return bytesToCharacters;
+}
+
+
+static const DWRITE_FONT_WEIGHT dwriteWeights[] = {
+	[uiDrawTextWeightThin] = DWRITE_FONT_WEIGHT_THIN,
+	[uiDrawTextWeightUltraLight] = DWRITE_FONT_WEIGHT_ULTRA_LIGHT,
+	[uiDrawTextWeightLight] = DWRITE_FONT_WEIGHT_LIGHT,
+	[uiDrawTextWeightBook] = DWRITE_FONT_WEIGHT_SEMI_LIGHT,
+	[uiDrawTextWeightNormal] = DWRITE_FONT_WEIGHT_NORMAL,
+	[uiDrawTextWeightMedium] = DWRITE_FONT_WEIGHT_MEDIUM,
+	[uiDrawTextWeightSemiBold] = DWRITE_FONT_WEIGHT_SEMI_BOLD,
+	[uiDrawTextWeightBold] = DWRITE_FONT_WEIGHT_BOLD,
+	[uiDrawTextWeightUtraBold] = DWRITE_FONT_WEIGHT_ULTRA_BOLD,
+	[uiDrawTextWeightHeavy] = DWRITE_FONT_WEIGHT_HEAVY,
+	[uiDrawTextWeightUltraHeavy] = DWRITE_FONT_WEIGHT_ULTRA_BLACK,
+};
+
+static const DWRITE_FONT_STYLE dwriteItalics[] = {
+	[uiDrawTextItalicNormal] = DWRITE_FONT_STYLE_NORMAL,
+	[uiDrawTextItalicOblique] = DWRITE_FONT_STYLE_OBLIQUE,
+	[uiDrawTextItalicItalic] = DWRITE_FONT_STYLE_ITALIC,
+};
+
+static const DWRITE_FONT_STRETCH dwriteStretches[] = {
+	[uiDrawTextStretchUltraCondensed] = DWRITE_FONT_STRETCH_ULTRA_CONDENSED,
+	[uiDrawTextStretchExtraCondensed] = DWRITE_FONT_STRETCH_EXTRA_CONDENSED,
+	[uiDrawTextStretchCondensed] = DWRITE_FONT_STRETCH_CONDENSED,
+	[uiDrawTextStretchSemiCondensed] = DWRITE_FONT_STRETCH_SEMI_CONDENSED,
+	[uiDrawTextStretchNormal] = DWRITE_FONT_STRETCH_NORMAL,
+	[uiDrawTextStretchSemiExpanded] = DWRITE_FONT_STRETCH_SEMI_EXPANDED,
+	[uiDrawTextStretchExpanded] = DWRITE_FONT_STRETCH_EXPANDED,
+	[uiDrawTextStretchExtraExpanded] = DWRITE_FONT_STRETCH_EXTRA_EXPANDED,
+	[uiDrawTextStretchUltraExpanded] = DWRITE_FONT_STRETCH_ULTRA_EXPANDED,
+};
+
+uiDrawTextLayout *uiDrawNewTextLayout(const char *text, const uiDrawInitialTextStyle *initialStyle)
+{
+	uiDrawTextLayout *layout;
+	WCHAR *family;
+	WCHAR *wtext;
+	intmax_t wlen;
+	HRESULT hr;
+
+	layout = uiNew(uiDrawTextLayout);
+
+	family = toUTF16(initialStyle->Family);
+	hr = dwfactory->CreateTextFormat(family,
+		NULL,
+		dwriteWeights[initialStyle->Weight],
+		dwriteItalics[initialStyle->Italic],
+		dwriteStretches[initialStyle->Stretch],
+		// typographic points are 1/72 inch; this parameter is 1/96 inch
+		// fortunately Microsoft does this too, in https://msdn.microsoft.com/en-us/library/windows/desktop/dd371554%28v=vs.85%29.aspx
+		initialStyle->Size * (96.0 / 72.0),
+		// see http://stackoverflow.com/questions/28397971/idwritefactorycreatetextformat-failing and https://msdn.microsoft.com/en-us/library/windows/desktop/dd368203.aspx
+		// TODO use the current locale again?
+		L"",
+		&(layout->format));
+	if (hr != S_OK)
+		logHRESULT("error creating IDWriteTextFormat in uiDrawNewTextLayout()", hr);
+	uiFree(family);
+	// TODO gravity
+
+	layout->bytesToCharacters = toUTF16Offsets(text, &wtext, &wlen);
+	hr = dwfactory->CreateTextLayout(wstr, wlen,
+		layout->format,
+		// FLOAT is float, not double, so this should work... TODO
+		FLT_MAX, FLT_MAX,
+		&(layout->layout));
+	if (hr != S_OK)
+		logHRESULT("error creating IDWriteTextLayout in uiDrawNewTextLayout()", hr);
+	uiFree(wtext);
+
+	return layout;
+}
+
+void uiDrawFreeTextLayout(uiDrawTextLayout *layout)
+{
+	layout->layout->Release();
+	layout->format->Release();
+	uiFree(layout);
+}
+
+void doDrawText(ID2D1RenderTarget *rt, ID2D1Brush *black, double x, double y, uiDrawTextLayout *layout)
+{
+	D2D1_POINT_2F pt;
+	HRESULT hr;
+
+	pt.x = x;
+	pt.y = y;
+	// TODO D2D1_DRAW_TEXT_OPTIONS_NO_SNAP?
+	// TODO D2D1_DRAW_TEXT_OPTIONS_CLIP?
+	// TODO when setting 8.1 as minimum, D2D1_DRAW_TEXT_OPTIONS_ENABLE_COLOR_FONT?
+	rt->DrawTextLayout(pt, layout->layout, black, D2D1_DRAW_TEXT_OPTIONS_NONE);
 }

windows/uipriv_windows.h

@@ -138,6 +138,7 @@ extern void freeContext(uiDrawContext *);
 // drawtext.cpp
 extern HRESULT initDrawText(void);
 extern void uninitDrawText(void);
+extern void doDrawText(ID2D1RenderTarget *rt, ID2D1Brush *black, double x, double y, uiDrawTextLayout *layout);
 
 #ifdef __cplusplus
 }