From 5521347322892f4997644925acfe1edf2c6b0bbf Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Sun, 3 Aug 2025 03:44:09 -0400
Subject: lib: liboda: Add oda_plotwin() window plotter

Introduce the oda_plotwin() function to allow one to plot a pixel onto a
window relative to the starting X/Y position of it. Plotting to (0,0)
draws to the top left corner of the window.

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 lib/liboda/include/liboda/oda.h |  18 +++++++
 lib/liboda/src/window.c         | 108 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 126 insertions(+)

(limited to 'lib')

diff --git a/lib/liboda/include/liboda/oda.h b/lib/liboda/include/liboda/oda.h
index d807a50..10738a9 100644
--- a/lib/liboda/include/liboda/oda.h
+++ b/lib/liboda/include/liboda/oda.h
@@ -80,8 +80,26 @@ struct oda_wattr {
     odadimm_t w, h;
 };
 
+/*
+ * A pixel point that can be plotted
+ * onto a window.
+ *
+ * @x,y: Point position
+ * @rgb: Color (RGB)
+ * @window: Window this will be plotted to
+ *
+ * Just set x, y, the color (rgb) then point it
+ * to a window!
+ */
+struct oda_point {
+    odapos_t x, y;
+    odacolor_t rgb;
+    struct oda_window *window;
+};
+
 int oda_reqwin(struct oda_wattr *params, struct oda_window **res);
 int oda_termwin(struct oda_state *state, struct oda_window *win);
+int oda_plotwin(struct oda_state *state, const struct oda_point *point);
 
 int oda_start_win(struct oda_state *state, struct oda_window *win);
 int oda_init(struct oda_state *res);
diff --git a/lib/liboda/src/window.c b/lib/liboda/src/window.c
index 876f89e..9a8b799 100644
--- a/lib/liboda/src/window.c
+++ b/lib/liboda/src/window.c
@@ -35,6 +35,114 @@
 #include <liboda/types.h>
 #include <libgfx/gfx.h>
 
+/*
+ * Check if a point is within the bounds of
+ * a surface.
+ *
+ * @wp: Surface to check with point
+ * @point: Point to check with surface
+ *
+ * Returns 0 if the check has passed,
+ * otherwise a less than zero value.
+ */
+static int
+oda_check_point(struct oda_window *wp, struct oda_point *point)
+{
+    struct gfx_shape *surf;
+    scrpos_t win_startx;
+    scrpos_t win_starty;
+    scrpos_t win_endx;
+    scrpos_t win_endy;
+
+    /* Compute start positions */
+    surf = &wp->surface;
+    win_startx = surf->x;
+    win_starty = surf->y;
+
+    /* Compute end positions */
+    win_endx = surf->x + surf->width;
+    win_endy = surf->y + surf->height;
+
+    /* Check X bounds */
+    if (point->x < win_startx || point->x > win_endx) {
+        return -1;
+    }
+
+    /* Check Y bounds */
+    if (point->y < win_starty || point->y > win_endy) {
+        return -1;
+    }
+
+    /* All good */
+    return 0;
+}
+
+/*
+ * Plot a pixel onto a window
+ *
+ * @state: ODA state pointer
+ * @point: Point to plot
+ *
+ * Returns 0 on success, otherwise a less than
+ * zero value.
+ *
+ * XXX: The x/y params in the 'point' argument must be
+ *      relative to the start of the window. In other words,
+ *      (0,0) refers to the top left corner of the window.
+ */
+int
+oda_plotwin(struct oda_state *state, const struct oda_point *point)
+{
+    struct gfx_point pixel;
+    struct oda_point point_new;
+    struct oda_window *window;
+    struct gfx_shape *surf;
+    odapos_t plotx, ploty;
+    int error;
+
+    if (state == NULL || point == NULL) {
+        return -EINVAL;
+    }
+
+    /* Validate cookie */
+    if ((error = oda_cookie_verify(state)) != 0) {
+        return error;
+    }
+
+    /* Try to grab the window */
+    if ((window = point->window) == NULL) {
+        return -EINVAL;
+    }
+
+    surf = &window->surface;
+    plotx = surf->x + point->x;
+    ploty = surf->y + point->y;
+
+    /*
+     * We are going to need to transform the coordinates
+     * as they are supposed to be coming in relative to
+     * the window bounds, e.g., (0,0) being the top left
+     * corner of a window.
+     */
+    point_new = *point;
+    point_new.x = plotx;
+    point_new.y = ploty;
+
+    /* Initialize the pixel to plot */
+    pixel.x = plotx;
+    pixel.y = ploty;
+    pixel.rgb = point->rgb;
+
+    /* Is the point within bounds? */
+    error = oda_check_point(window, &point_new);
+    if (error < 0) {
+        return error;
+    }
+
+    gfx_plot_point(&state->gctx, &pixel);
+    return 0;
+}
+
 /*
  * Request a window from the OSMORA Display
  * Architecture (ODA).
-- 
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