console: Allow measuring the bounding box of text

For laying out text accurately it is necessary to know the width and
height of the text. Add a measure() method to the console API, so this
can be supported.

Add an implementation for truetype and a base implementation for the
normal console.

Signed-off-by: Simon Glass <sjg@chromium.org>

2 files changed, 84 insertions, 2 deletions

diff --git a/drivers/video/console_truetype.c b/drivers/video/console_truetype.c
index 6f3fc82f9b0..288123a2e06 100644
--- a/drivers/video/console_truetype.c
+++ b/drivers/video/console_truetype.c
@@ -614,8 +614,8 @@ static void select_metrics(struct udevice *dev, struct console_tt_metrics *met)
 	vc_priv->tab_width_frac = VID_TO_POS(met->font_size) * 8 / 2;
 }
 
-static int truetype_select_font(struct udevice *dev, const char *name,
-				uint size)
+static int get_metrics(struct udevice *dev, const char *name, uint size,
+		       struct console_tt_metrics **metp)
 {
 	struct console_tt_priv *priv = dev_get_priv(dev);
 	struct console_tt_metrics *met;
@@ -653,11 +653,70 @@ static int truetype_select_font(struct udevice *dev, const char *name,
 		met = priv->metrics;
 	}
 
+	*metp = met;
+
+	return 0;
+}
+
+static int truetype_select_font(struct udevice *dev, const char *name,
+				uint size)
+{
+	struct console_tt_metrics *met;
+	int ret;
+
+	ret = get_metrics(dev, name, size, &met);
+	if (ret)
+		return log_msg_ret("sel", ret);
+
 	select_metrics(dev, met);
 
 	return 0;
 }
 
+int truetype_measure(struct udevice *dev, const char *name, uint size,
+		     const char *text, struct vidconsole_bbox *bbox)
+{
+	struct console_tt_metrics *met;
+	stbtt_fontinfo *font;
+	int lsb, advance;
+	const char *s;
+	int width;
+	int last;
+	int ret;
+
+	ret = get_metrics(dev, name, size, &met);
+	if (ret)
+		return log_msg_ret("sel", ret);
+
+	bbox->valid = false;
+	if (!*text)
+		return 0;
+
+	font = &met->font;
+	width = 0;
+	for (last = 0, s = text; *s; s++) {
+		int ch = *s;
+
+		/* Used kerning to fine-tune the position of this character */
+		if (last)
+			width += stbtt_GetCodepointKernAdvance(font, last, ch);
+
+		/* First get some basic metrics about this character */
+		stbtt_GetCodepointHMetrics(font, ch, &advance, &lsb);
+
+		width += advance;
+		last = ch;
+	}
+
+	bbox->valid = true;
+	bbox->x0 = 0;
+	bbox->y0 = 0;
+	bbox->x1 = tt_ceil((double)width * met->scale);
+	bbox->y1 = met->font_size;
+
+	return 0;
+}
+
 const char *console_truetype_get_font_size(struct udevice *dev, uint *sizep)
 {
 	struct console_tt_priv *priv = dev_get_priv(dev);
@@ -709,6 +768,7 @@ struct vidconsole_ops console_truetype_ops = {
 	.get_font	= console_truetype_get_font,
 	.get_font_size	= console_truetype_get_font_size,
 	.select_font	= truetype_select_font,
+	.measure	= truetype_measure,
 };
 
 U_BOOT_DRIVER(vidconsole_truetype) = {
diff --git a/drivers/video/vidconsole-uclass.c b/drivers/video/vidconsole-uclass.c
index 3f89537c47b..05f93047809 100644
--- a/drivers/video/vidconsole-uclass.c
+++ b/drivers/video/vidconsole-uclass.c
@@ -596,6 +596,28 @@ int vidconsole_select_font(struct udevice *dev, const char *name, uint size)
 	return ops->select_font(dev, name, size);
 }
 
+int vidconsole_measure(struct udevice *dev, const char *name, uint size,
+		       const char *text, struct vidconsole_bbox *bbox)
+{
+	struct vidconsole_priv *priv = dev_get_uclass_priv(dev);
+	struct vidconsole_ops *ops = vidconsole_get_ops(dev);
+	int ret;
+
+	if (ops->select_font) {
+		ret = ops->measure(dev, name, size, text, bbox);
+		if (ret != -ENOSYS)
+			return ret;
+	}
+
+	bbox->valid = true;
+	bbox->x0 = 0;
+	bbox->y0 = 0;
+	bbox->x1 = priv->x_charsize * strlen(text);
+	bbox->y1 = priv->y_charsize;
+
+	return 0;
+}
+
 void vidconsole_push_colour(struct udevice *dev, enum colour_idx fg,
 			    enum colour_idx bg, struct vidconsole_colour *old)
 {