video: Use fractional units for X coordinates
With anti-aliased fonts we need a more fine-grained horizontal position
than a single pixel. Characters can be positioned to start part-way through
a pixel, with anti-aliasing (greyscale edges) taking care of the visual
effect.
To cope with this, use fractional units (1/256 pixel) for horizontal
positions in the text console.
Signed-off-by: Simon Glass <sjg@chromium.org>
[agust: rebased]
Signed-off-by: Anatolij Gustschin <agust@denx.de>
diff --git a/include/video_console.h b/include/video_console.h
index c0fc792..eeba368 100644
--- a/include/video_console.h
+++ b/include/video_console.h
@@ -7,21 +7,37 @@
#ifndef __video_console_h
#define __video_console_h
+#define VID_FRAC_DIV 256
+
+#define VID_TO_PIXEL(x) ((x) / VID_FRAC_DIV)
+#define VID_TO_POS(x) ((x) * VID_FRAC_DIV)
+
/**
* struct vidconsole_priv - uclass-private data about a console device
*
+ * Drivers must set up @rows, @cols, @x_charsize, @y_charsize in their probe()
+ * method. Drivers may set up @xstart_frac if desired.
+ *
* @sdev: stdio device, acting as an output sink
- * @curr_col: Current text column (0=left)
- * @curr_row: Current row (0=top)
+ * @xcur_frac: Current X position, in fractional units (VID_TO_POS(x))
+ * @curr_row: Current Y position in pixels (0=top)
* @rows: Number of text rows
* @cols: Number of text columns
+ * @x_charsize: Character width in pixels
+ * @y_charsize: Character height in pixels
+ * @tab_width_frac: Tab width in fractional units
+ * @xsize_frac: Width of the display in fractional units
*/
struct vidconsole_priv {
struct stdio_dev sdev;
- int curr_col;
- int curr_row;
+ int xcur_frac;
+ int ycur;
int rows;
int cols;
+ int x_charsize;
+ int y_charsize;
+ int tab_width_frac;
+ int xsize_frac;
};
/**
@@ -36,12 +52,15 @@
* putc_xy() - write a single character to a position
*
* @dev: Device to write to
- * @x: Pixel X position (0=left-most pixel)
+ * @x_frac: Fractional pixel X position (0=left-most pixel) which
+ * is the X position multipled by VID_FRAC_DIV.
* @y: Pixel Y position (0=top-most pixel)
* @ch: Character to write
- * @return 0 if OK, -ve on error
+ * @return number of fractional pixels that the cursor should move,
+ * if all is OK, -EAGAIN if we ran out of space on this line, other -ve
+ * on error
*/
- int (*putc_xy)(struct udevice *dev, uint x, uint y, char ch);
+ int (*putc_xy)(struct udevice *dev, uint x_frac, uint y, char ch);
/**
* move_rows() - Move text rows from one place to another
@@ -75,10 +94,13 @@
* vidconsole_putc_xy() - write a single character to a position
*
* @dev: Device to write to
- * @x: Pixel X position (0=left-most pixel)
+ * @x_frac: Fractional pixel X position (0=left-most pixel) which
+ * is the X position multipled by VID_FRAC_DIV.
* @y: Pixel Y position (0=top-most pixel)
* @ch: Character to write
- * @return 0 if OK, -ve on error
+ * @return number of fractional pixels that the cursor should move,
+ * if all is OK, -EAGAIN if we ran out of space on this line, other -ve
+ * on error
*/
int vidconsole_putc_xy(struct udevice *dev, uint x, uint y, char ch);
