video: Begin support for measuring multiple lines of text

Update the vidconsole API so that measure() can measure multiple lines
of text. This will make it easier to implement multi-line fields in
expo.

Tidy up the function comments while we are here.

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

boot/scene.c

@@ -298,7 +298,7 @@ int scene_obj_get_hw(struct scene *scn, uint id, int *widthp)
 		}
 
 		ret = vidconsole_measure(scn->expo->cons, txt->font_name,
-					 txt->font_size, str, &bbox);
+					 txt->font_size, str, &bbox, NULL);
 		if (ret)
 			return log_msg_ret("mea", ret);
 		if (widthp)

drivers/video/console_truetype.c

@@ -733,7 +733,8 @@ static int truetype_select_font(struct udevice *dev, const char *name,
 }
 
 static int truetype_measure(struct udevice *dev, const char *name, uint size,
-			    const char *text, struct vidconsole_bbox *bbox)
+			    const char *text, struct vidconsole_bbox *bbox,
+			    struct alist *lines)
 {
 	struct console_tt_metrics *met;
 	stbtt_fontinfo *font;

drivers/video/vidconsole-uclass.c

@@ -608,14 +608,17 @@ int vidconsole_select_font(struct udevice *dev, const char *name, uint size)
 }
 
 int vidconsole_measure(struct udevice *dev, const char *name, uint size,
-		       const char *text, struct vidconsole_bbox *bbox)
+		       const char *text, struct vidconsole_bbox *bbox,
+		       struct alist *lines)
 {
 	struct vidconsole_priv *priv = dev_get_uclass_priv(dev);
 	struct vidconsole_ops *ops = vidconsole_get_ops(dev);
 	int ret;
 
 	if (ops->measure) {
-		ret = ops->measure(dev, name, size, text, bbox);
+		if (lines)
+			alist_empty(lines);
+		ret = ops->measure(dev, name, size, text, bbox, lines);
 		if (ret != -ENOSYS)
 			return ret;
 	}

include/video_console.h

@@ -6,6 +6,7 @@
 #ifndef __video_console_h
 #define __video_console_h
 
+#include <alist.h>
 #include <video.h>
 
 struct abuf;
@@ -119,6 +120,19 @@ struct vidconsole_bbox {
 	int y1;
 };
 
+/**
+ * vidconsole_mline - Holds information about a line of measured text
+ *
+ * @bbox: Bounding box of the line, assuming it starts at 0,0
+ * @start: String index of the first character in the line
+ * @len: Number of characters in the line
+ */
+struct vidconsole_mline {
+	struct vidconsole_bbox bbox;
+	int start;
+	int len;
+};
+
 /**
  * struct vidconsole_ops - Video console operations
  *
@@ -228,18 +242,23 @@ struct vidconsole_ops {
 	int (*select_font)(struct udevice *dev, const char *name, uint size);
 
 	/**
-	 * measure() - Measure the bounds of some text
+	 * measure() - Measure the bounding box of some text
 	 *
-	 * @dev:	Device to adjust
+	 * @dev:	Console device to use
 	 * @name:	Font name to use (NULL to use default)
 	 * @size:	Font size to use (0 to use default)
 	 * @text:	Text to measure
 	 * @bbox:	Returns bounding box of text, assuming it is positioned
 	 *		at 0,0
+	 * @lines:	If non-NULL, this must be an alist of
+	 *		struct vidconsole_mline inited by caller. A separate
+	 *		record is added for each line of text
+	 *
 	 * Returns: 0 on success, -ENOENT if no such font
 	 */
 	int (*measure)(struct udevice *dev, const char *name, uint size,
-		       const char *text, struct vidconsole_bbox *bbox);
+		       const char *text, struct vidconsole_bbox *bbox,
+		       struct alist *lines);
 
 	/**
 	 * nominal() - Measure the expected width of a line of text
@@ -320,19 +339,24 @@ int vidconsole_get_font(struct udevice *dev, int seq,
  */
 int vidconsole_select_font(struct udevice *dev, const char *name, uint size);
 
-/*
- * vidconsole_measure() - Measuring the bounding box of some text
+/**
+ * vidconsole_measure() - Measure the bounding box of some text
  *
- * @dev: Console device to use
- * @name: Font name, NULL for default
- * @size: Font size, ignored if @name is NULL
- * @text: Text to measure
- * @bbox: Returns nounding box of text
- * Returns: 0 if OK, -ve on error
+ * @dev:	Device to adjust
+ * @name:	Font name to use (NULL to use default)
+ * @size:	Font size to use (0 to use default)
+ * @text:	Text to measure
+ * @bbox:	Returns bounding box of text, assuming it is positioned
+ *		at 0,0
+ * @lines:	If non-NULL, this must be an alist of
+ *		struct vidconsole_mline inited by caller. The list is emptied
+ *		and then a separate record is added for each line of text
+ *
+ * Returns: 0 on success, -ENOENT if no such font
  */
 int vidconsole_measure(struct udevice *dev, const char *name, uint size,
-		       const char *text, struct vidconsole_bbox *bbox);
-
+		       const char *text, struct vidconsole_bbox *bbox,
+		       struct alist *lines);
 /**
  * vidconsole_nominal() - Measure the expected width of a line of text
  *

test/dm/video.c

@@ -788,6 +788,7 @@ static int dm_test_font_measure(struct unit_test_state *uts)
 	struct vidconsole_bbox bbox;
 	struct video_priv *priv;
 	struct udevice *dev, *con;
+	struct alist lines;
 
 	ut_assertok(uclass_get_device(UCLASS_VIDEO, 0, &dev));
 	priv = dev_get_uclass_priv(dev);
@@ -797,11 +798,13 @@ static int dm_test_font_measure(struct unit_test_state *uts)
 	/* this is using the Nimbus font with size of 18 pixels */
 	ut_assertok(uclass_get_device(UCLASS_VIDEO_CONSOLE, 0, &con));
 	vidconsole_position_cursor(con, 0, 0);
-	ut_assertok(vidconsole_measure(con, NULL, 0, test_string, &bbox));
+	ut_assertok(vidconsole_measure(con, NULL, 0, test_string, &bbox,
+				       &lines));
 	ut_asserteq(0, bbox.x0);
 	ut_asserteq(0, bbox.y0);
 	ut_asserteq(0x47a, bbox.x1);
 	ut_asserteq(0x12, bbox.y1);
+	ut_asserteq(0, lines.count);
 
 	return 0;
 }