Added multi-line text drawing

- fixed some warnings
- changed nvgLetterSpacing() to nvgTextLetterSpacing()
- added nvgTextBox()
- added nvgTextLineHeight()
- added some documentation

example/demo.c

@@ -818,6 +818,7 @@ void drawParagraph(struct NVGcontext* vg, float x, float y, float width, float h
 	int nrows, i, nglyphs, j;
 	float lineh;
 	float caretx, px;
+	NVG_NOTUSED(height);
 
 	nvgSave(vg);
 
@@ -872,6 +873,15 @@ void drawParagraph(struct NVGcontext* vg, float x, float y, float width, float h
 		start = rows[nrows-1].next;
 	}
 
+	y += 10.0f;
+
+	nvgFillColor(vg, nvgRGBA(0,0,0,220));
+	nvgFontSize(vg, 12.0f);
+	nvgTextAlign(vg, NVG_ALIGN_LEFT|NVG_ALIGN_TOP);
+	nvgTextLineHeight(vg, 1.2f);
+
+	nvgTextBox(vg, x,y, 150, "Hover your mouse over the text to see calculated caret position.", NULL);
+
 	nvgRestore(vg);
 }
 

src/nanovg.c

@@ -66,6 +66,7 @@ struct NVGstate {
 	struct NVGscissor scissor;
 	float fontSize;
 	float letterSpacing;
+	float lineHeight;
 	float fontBlur;
 	int textAlign;
 	int fontId;
@@ -290,13 +291,23 @@ struct NVGcolor nvgRGBf(float r, float g, float b)
 
 struct NVGcolor nvgRGBA(unsigned char r, unsigned char g, unsigned char b, unsigned char a)
 {
-	struct NVGcolor color = {r/255.0f, g/255.0f, b/255.0f, a/255.0f};
+	struct NVGcolor color;
+	// Use longer initialization to suppress warning.
+	color.r = r / 255.0f;
+	color.g = g / 255.0f;
+	color.b = b / 255.0f;
+	color.a = a / 255.0f;
 	return color;
 }
 
 struct NVGcolor nvgRGBAf(float r, float g, float b, float a)
 {
-	struct NVGcolor color = {r, g, b, a};
+	struct NVGcolor color;
+	// Use longer initialization to suppress warning.
+	color.r = r;
+	color.g = g;
+	color.b = b;
+	color.a = a;
 	return color;
 }
 
@@ -466,6 +477,7 @@ void nvgReset(struct NVGcontext* ctx)
 
 	state->fontSize = 16.0f;
 	state->letterSpacing = 0.0f;
+	state->lineHeight = 0.0f;
 	state->fontBlur = 0.0f;
 	state->textAlign = NVG_ALIGN_LEFT | NVG_ALIGN_BASELINE;
 	state->fontId = 0;
@@ -574,7 +586,7 @@ int nvgCreateImage(struct NVGcontext* ctx, const char* filename)
 	return image;
 }
 
-int nvgCreateImageMem(struct NVGcontext* ctx, unsigned char* data, int ndata, int freeData)
+int nvgCreateImageMem(struct NVGcontext* ctx, unsigned char* data, int ndata)
 {
 	int w, h, n, image;
 	unsigned char* img = stbi_load_from_memory(data, ndata, &w, &h, &n, 4);
@@ -616,7 +628,7 @@ struct NVGpaint nvgLinearGradient(struct NVGcontext* ctx,
 	struct NVGpaint p;
 	float dx, dy, d;
 	const float large = 1e5;
-
+	NVG_NOTUSED(ctx);
 	memset(&p, 0, sizeof(p));
 
 	// Calculate transform aligned to the line
@@ -655,7 +667,7 @@ struct NVGpaint nvgRadialGradient(struct NVGcontext* ctx,
 	struct NVGpaint p;
 	float r = (inr+outr)*0.5f;
 	float f = (outr-inr);
-
+	NVG_NOTUSED(ctx);
 	memset(&p, 0, sizeof(p));
 
 	nvg__xformIdentity(p.xform);
@@ -680,7 +692,7 @@ struct NVGpaint nvgBoxGradient(struct NVGcontext* ctx,
 							   struct NVGcolor icol, struct NVGcolor ocol)
 {
 	struct NVGpaint p;
-
+	NVG_NOTUSED(ctx);
 	memset(&p, 0, sizeof(p));
 
 	nvg__xformIdentity(p.xform);
@@ -706,7 +718,7 @@ struct NVGpaint nvgImagePattern(struct NVGcontext* ctx,
 								int image, int repeat)
 {
 	struct NVGpaint p;
-
+	NVG_NOTUSED(ctx);
 	memset(&p, 0, sizeof(p));
 
 	nvg__xformRotate(p.xform, angle);
@@ -1873,16 +1885,22 @@ void nvgFontSize(struct NVGcontext* ctx, float size)
 	state->fontSize = size;
 }
 
-void nvgLetterSpacing(struct NVGcontext* ctx, float spacing)
+void nvgFontBlur(struct NVGcontext* ctx, float blur)
+{
+	struct NVGstate* state = nvg__getState(ctx);
+	state->fontBlur = blur;
+}
+
+void nvgTextLetterSpacing(struct NVGcontext* ctx, float spacing)
 {
 	struct NVGstate* state = nvg__getState(ctx);
 	state->letterSpacing = spacing;
 }
 
-void nvgFontBlur(struct NVGcontext* ctx, float blur)
+void nvgTextLineHeight(struct NVGcontext* ctx, float lineHeight)
 {
 	struct NVGstate* state = nvg__getState(ctx);
-	state->fontBlur = blur;
+	state->lineHeight = lineHeight;
 }
 
 void nvgTextAlign(struct NVGcontext* ctx, int align)
@@ -1984,6 +2002,41 @@ float nvgText(struct NVGcontext* ctx, float x, float y, const char* string, cons
 	return iter.x;
 }
 
+float nvgTextBox(struct NVGcontext* ctx, float x, float y, float width, const char* string, const char* end)
+{
+	struct NVGstate* state = nvg__getState(ctx);
+	struct NVGtextRow rows[2];
+	int nrows = 0, i;
+	int oldAlign = state->textAlign;
+	int haling = state->textAlign & (NVG_ALIGN_LEFT | NVG_ALIGN_CENTER | NVG_ALIGN_RIGHT);
+	int valign = state->textAlign & (NVG_ALIGN_TOP | NVG_ALIGN_MIDDLE | NVG_ALIGN_BOTTOM | NVG_ALIGN_BASELINE);
+	float lineh = 0;
+
+	if (state->fontId == FONS_INVALID) return x;
+
+	nvgTextMetrics(ctx, NULL, NULL, &lineh);
+
+	state->textAlign = NVG_ALIGN_LEFT | valign;
+
+	while ((nrows = nvgTextBreakLines(ctx, string, end, width, rows, 2))) {
+		for (i = 0; i < nrows; i++) {
+			struct NVGtextRow* row = &rows[i];
+			if (haling & NVG_ALIGN_LEFT)
+				nvgText(ctx, x, y, row->start, row->end);
+			else if (haling & NVG_ALIGN_CENTER)
+				nvgText(ctx, x + width*0.5f - row->width*0.5f, y, row->start, row->end);
+			else if (haling & NVG_ALIGN_RIGHT)
+				nvgText(ctx, x + width - row->width, y, row->start, row->end);
+			y += lineh * state->lineHeight;
+		}
+		string = rows[nrows-1].next;
+	}
+
+	state->textAlign = oldAlign;
+
+	return 0; // TODO
+}
+
 int nvgTextGlyphPositions(struct NVGcontext* ctx, const char* string, const char* end, float x, float y, struct NVGglyphPosition* positions, int maxPositions)
 {
 	struct NVGstate* state = nvg__getState(ctx);

src/nanovg.h

@@ -27,20 +27,16 @@ extern "C" {
 
 struct NVGcontext;
 
-struct NVGcolor
-{
-	union
-	{
+struct NVGcolor {
+	union {
 		float rgba[4];
-		struct
-		{
+		struct {
 			float r,g,b,a;
 		};
 	};
 };
 
-struct NVGpaint
-{
+struct NVGpaint {
 	float xform[6];
 	float extent[2];
 	float radius;
@@ -91,6 +87,19 @@ enum NVGalpha {
 	NVG_PREMULTIPLIED_ALPHA,
 };
 
+struct NVGglyphPosition {
+	const char* str;	// Position of the glyph in the input string.
+	float x;			// The x- coordinate of the position of the glyph .
+};
+
+struct NVGtextRow {
+	const char* start;	// Pointer to the input text where the row starts.
+	const char* end;	// Pointer to the input text where the row ends (one past the last character).
+	const char* next;	// Pointer to the beginning of the next row.
+	float width;		// Width of the row.
+};
+
+
 // Begin drawing a new frame
 // Calls to nanovg drawing API should be wrapped in nvgBeginFrame() & nvgEndFrame()
 // nvgBeginFrame() defines the size of the window to render to in relation currently
@@ -243,9 +252,9 @@ void nvgScale(struct NVGcontext* ctx, float x, float y);
 // Returns handle to the image.
 int nvgCreateImage(struct NVGcontext* ctx, const char* filename);
 
-// Creates image by loading it from the specified memory chunk.
+// Creates image by loading it from the specified chunk of memory.
 // Returns handle to the image.
-int nvgCreateImageMem(struct NVGcontext* ctx, unsigned char* data, int ndata, int freeData);
+int nvgCreateImageMem(struct NVGcontext* ctx, unsigned char* data, int ndata);
 
 // Creates image from specified image data.
 // Returns handle to the image.
@@ -394,12 +403,15 @@ int nvgFindFont(struct NVGcontext* ctx, const char* name);
 // Sets the font size of current text style.
 void nvgFontSize(struct NVGcontext* ctx, float size);
 
-// Sets the letter spacing of current text style.
-void nvgLetterSpacing(struct NVGcontext* ctx, float spacing);
-
 // Sets the blur of current text style.
 void nvgFontBlur(struct NVGcontext* ctx, float blur);
 
+// Sets the letter spacing of current text style.
+void nvgTextLetterSpacing(struct NVGcontext* ctx, float spacing);
+
+// Sets the proportional line height of current text style. The line height is specified as multiple of font size. 
+void nvgTextLineHeight(struct NVGcontext* ctx, float lineHeight);
+
 // Sets the text align of current text style, see NVGaling for options.
 void nvgTextAlign(struct NVGcontext* ctx, int align);
 
@@ -412,6 +424,11 @@ void nvgFontFace(struct NVGcontext* ctx, const char* font);
 // Draws text string at specified location. If end is specified only the sub-string up to the end is drawn.
 float nvgText(struct NVGcontext* ctx, float x, float y, const char* string, const char* end);
 
+// Draws multi-line text string at specified location wrapped at the specified width. If end is specified only the sub-string up to the end is drawn.
+// White space is stripped at the beginning of the rows, the text is split at word boundaries or when new-line characters are encountered.
+// Words longer than the max width are slit at nearest character (i.e. no hyphenation).
+float nvgTextBox(struct NVGcontext* ctx, float x, float y, float width, const char* string, const char* end);
+
 // Measures the specified text string. Parameter bounds should be a pointer to float[4] if 
 // the bounding box of the text should be returned. Returns the width of the measured text.
 // Current transform does not affect the measured values.
@@ -421,18 +438,12 @@ float nvgTextBounds(struct NVGcontext* ctx, const char* string, const char* end,
 // Current transform does not affect the measured values.
 void nvgTextMetrics(struct NVGcontext* ctx, float* ascender, float* descender, float* lineh);
 
-struct NVGglyphPosition {
-	const char* str;
-	float x;
-};
+// Calculates the glyph x positions of the specified text. If end is specified only the sub-string will be used.
 int nvgTextGlyphPositions(struct NVGcontext* ctx, const char* string, const char* end, float x, float y, struct NVGglyphPosition* positions, int maxPositions);
 
-struct NVGtextRow {
-	const char* start;
-	const char* end;
-	const char* next;
-	float width;
-};
+// Breaks the specified text into lines. If end is specified only the sub-string will be used.
+// White space is stripped at the beginning of the rows, the text is split at word boundaries or when new-line characters are encountered.
+// Words longer than the max width are slit at nearest character (i.e. no hyphenation).
 int nvgTextBreakLines(struct NVGcontext* ctx, const char* string, const char* end, float maxRowWidth, struct NVGtextRow* rows, int maxRows);
 
 //