getTextBounds missing

[stanzlavos]

Hi

First of all, thanks for this fast lib. :)

Any plans to add "getTextBounds" API ? If not, I could try to add something and raise a pull request ?

[Bodmer]

The "Free Fonts" can be rendered with background (unlike the stock Adafruit_GFX library) so I did not see a need for a getTextBounds function. See the "TFT_Custom_Fonts" or "Free_Font_Demo" examples.

When a "Free Font" is selected the library scans all characters in the set to determine the maximum y coordinate limits, so the background box always has the same height irrespective of what characters are drawn. This makes life easier as you don't need to do the messy box and erase coding yourself.

You can also add width padding to the background, so old text gets erased when over-writing. This is particularly useful for numbers that change as the erased box width can be fixed to be larger that the maximum digit count.

A getTextBounds function is clearly possible but would need to take into account the feature of the library to set the text coordinate datum (see "Free_Font_Demo" example).

[stanzlavos]

Hi I am not a font expert :D, but there could be fonts that don't have this background ? I mean, the default font that I was using did not. And, I like such fonts too. When I make custom buttons or any UI element that is drawn using a BMP and then needs text on top of it, fonts with background cannot be used. :)

…

On 13-Apr-2017 4:24 AM, "Bodmer" ***@***.***> wrote: The "Free Fonts" can be rendered with background (unlike the stock Adafruit_GFX library) so I did not see a need for a getTextBounds function. See the "TFT_Custom_Fonts" or "Free_Font_Demo" examples. When a "Free Font" is selected the library scans all characters in the set to determine the maximum y coordinate limits, so the background box always has the same height irrespective of what characters are drawn. This makes life easier as you don't need to do the messy box and erase coding yourself. You can also add width padding to the background, so old text gets erased when over-writing. This is particularly useful for numbers that change as the erased box width can be fixed to be larger that the maximum digit count. A getTextBounds function is clearly possible but would need to take into account the feature of the library to set the text coordinate datum (see "Free_Font_Demo" example). — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#6 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AY1oK2qo7Pf2b47hR3D4iEUlKL7TgMV3ks5rvVYlgaJpZM4M39Da> .

[Bodmer]

The sketch decides if the font is drawn with background or not, e.g.:

tft.setTextColor(TFT_WHITE, TFT_BLACK); // White characters with black background

tft.setTextColor(TFT_WHITE); // White characters no (transparent) background

The text can then be drawn using the drawString() function

If the print() method is used then background is not rendered for the FreeFonts for technical reasons (due to streaming of characters)

P.S. For centering text within a button frame use the setTextDatum(MC_DATUM) function and plot text at center coord of button (makes life easy!)

[stanzlavos]

Ok. :)

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On Apr 14, 2017 6:46 AM, "Bodmer" ***@***.***> wrote: The sketch decides if he font is drawn with background or not, e.g.: tft.setTextColor(TFT_WHITE, TFT_BLACK); // White characters with black background tft.setTextColor(TFT_WHITE); // White characters no (transparent) background The text can then be drawn using the drawString() function If the print() method is used then background is not rendered for the FreeFonts for technical reasons (due to streaming of characters) — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#6 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AY1oK5PU8I6M5utQyPk37Zp1mTswUr0Aks5rvsjSgaJpZM4M39Da> .

[wilhelmzeuschner]

@stanzlavos I don't knwo whether this is still in any way relevant to you now but here's my quick and improvised solution (I essentially copied the code from the Adafruit GFX library and changed a few things so that now errors occurred during compilation).

Paste this code into your sketch:

void getTextBounds(const char *str, int16_t x, int16_t y,
	int16_t *x1, int16_t *y1, uint16_t *w, uint16_t *h) {
	uint8_t c; // Current character

	*x1 = x;
	*y1 = y;
	*w = *h = 0;

	int16_t minx = tft.width(), miny = tft.width(), maxx = -1, maxy = -1;

	while ((c = *str++))
		charBounds(c, &x, &y, &minx, &miny, &maxx, &maxy);

	if (maxx >= minx) {
		*x1 = minx;
		*w = maxx - minx + 1;
	}
	if (maxy >= miny) {
		*y1 = miny;
		*h = maxy - miny + 1;
	}
}

void charBounds(char c, int16_t *x, int16_t *y,
	int16_t *minx, int16_t *miny, int16_t *maxx, int16_t *maxy) {

	if (!true) {	//If non-default font is used not usable in my quick "hack"

		//if (c == '\n') { // Newline?
		//	*x = 0;    // Reset x to zero, advance y by one line
		//	*y += textsize * (uint8_t)pgm_read_byte(&gfxFont->yAdvance);
		//}
		//else if (c != '\r') { // Not a carriage return; is normal char
		//	uint8_t first = pgm_read_byte(&gfxFont->first),
		//		last = pgm_read_byte(&gfxFont->last);
		//	if ((c >= first) && (c <= last)) { // Char present in this font?
		//		GFXglyph *glyph = &(((GFXglyph *)pgm_read_pointer(
		//			&gfxFont->glyph))[c - first]);
		//		uint8_t gw = pgm_read_byte(&glyph->width),
		//			gh = pgm_read_byte(&glyph->height),
		//			xa = pgm_read_byte(&glyph->xAdvance);
		//		int8_t  xo = pgm_read_byte(&glyph->xOffset),
		//			yo = pgm_read_byte(&glyph->yOffset);
		//		if (wrap && ((*x + (((int16_t)xo + gw)*textsize)) > _width)) {
		//			*x = 0; // Reset x to zero, advance y by one line
		//			*y += textsize * (uint8_t)pgm_read_byte(&gfxFont->yAdvance);
		//		}
		//		int16_t ts = (int16_t)textsize,
		//			x1 = *x + xo * ts,
		//			y1 = *y + yo * ts,
		//			x2 = x1 + gw * ts - 1,
		//			y2 = y1 + gh * ts - 1;
		//		if (x1 < *minx) *minx = x1;
		//		if (y1 < *miny) *miny = y1;
		//		if (x2 > *maxx) *maxx = x2;
		//		if (y2 > *maxy) *maxy = y2;
		//		*x += xa * ts;
		//	}
		//}

	}
	else { // Default font

		if (c == '\n') {                     // Newline?
			*x = 0;                        // Reset x to zero,
			*y += tft.textsize * 8;             // advance y one line
			// min/max x/y unchaged -- that waits for next 'normal' character
		}
		else if (c != '\r') {  // Normal char; ignore carriage returns
			if (/*wrap*/ false && ((*x + tft.textsize * 6) > tft.width())) { // Off right?
				*x = 0;                    // Reset x to zero,
				*y += tft.textsize * 8;         // advance y one line
			}
			int x2 = *x + tft.textsize * 6 - 1, // Lower-right pixel of char
				y2 = *y + tft.textsize * 8 - 1;
			if (x2 > *maxx) *maxx = x2;      // Track max x, y
			if (y2 > *maxy) *maxy = y2;
			if (*x < *minx) *minx = *x;      // Track min x, y
			if (*y < *miny) *miny = *y;
			*x += tft.textsize * 6;             // Advance x one char
		}
	}
}