Add conditional redrawing

This covers most of the previous functionality, but separating the input
handling and rendering functions. Only cursor drawing and a few corner
cases missing.

3 files changed, 63 insertions, 44 deletions

diff --git a/src/drawing.c b/src/drawing.c
index b790595..89d3ef6 100644
--- a/src/drawing.c
+++ b/src/drawing.c
@@ -29,7 +29,7 @@ draw_channels(void) {
         }
         u8 clr = active ? COL_FG : COL_GREY;
         size_t y = CHAN_START_Y + i * CHAN_OFFSET_Y;
-        draw_channel_sprite(CHAN_START_X, y, active, i);
+        draw_channel_sprite(CHAN_START_X, y, clr, i);
     }
 }
 
@@ -175,8 +175,12 @@ draw_bank_buttons() {
 
 void
 draw_pattern_buttons() {
+    // Clear patterns.
     size_t x = PAT_START_X;
     size_t y = PAT_START_Y;
+
+    draw_filled_rect(x, y, x + PAT_W, y + PAT_H * 8, COL_BG);
+
     txt_drawf_small("PAT", x, y - 10, COL_FG);
     char pat_names[] = {
         'A', 'B', 'C', 'D',
@@ -190,7 +194,6 @@ draw_pattern_buttons() {
         if (i == next_pattern && current_pattern != next_pattern) {
             color = COL_BLUE;
         }
-        draw_filled_rect(x, y, x + PAT_W, y + PAT_H, COL_BG);
         draw_rect(x, y, x + PAT_W, y + PAT_H, color);
         txt_drawc(pat_names[i], x + 4, y + 2, color);
         y += PAT_OFFSET_Y;
diff --git a/src/main.c b/src/main.c
index 8ee4945..b6be6b9 100644
--- a/src/main.c
+++ b/src/main.c
@@ -21,27 +21,53 @@ WITH REGARD TO THIS SOFTWARE.
 
 void
 render(void) {
-    // TODO: Make sure we are drawing the proper cursor color.
     // TODO: Decouple update from rendering.
-    PROF(screen_fill(0), clear_cycles);
+    // PROF(screen_fill(0), clear_cycles);
     PROF(draw_rect(0, 0, SCREEN_WIDTH - 1, SCREEN_HEIGHT - 1, 1), clear_cycles);
-    PROF(draw_triggers(), draw_trigs_cycles);
-    PROF(draw_channels(), draw_btn_cycles);
-    PROF(draw_pattern_buttons(), draw_btn_cycles);
-    PROF(draw_bank_buttons(), draw_btn_cycles);
-    PROF(draw_bpm(), draw_btn_cycles);
-    PROF(draw_play(), draw_btn_cycles);
-    PROF(draw_stop(), draw_btn_cycles);
-    PROF(draw_piano(), draw_piano_cycles);
-    // TODO: Draw the notes currently playing with a fade off animation for the
-    // first 3 channels.
-    TriggerNote *trig = get_current_trig();
-    PROF(draw_note(trig->note, COL_NOTE_PRESSED), draw_piano_cycles);
-    PROF(draw_parameters(), draw_param_cycles);
-    PROF(draw_trig_cursor(trig_selection_loc, COL_CURSOR), draw_cursor_cycles);
-    PROF(draw_channel_cursor(channel_selection_loc, COL_GREY), draw_cursor_cycles);
-    PROF(draw_pattern_cursor(pattern_selection_loc, COL_GREY), draw_cursor_cycles);
-    PROF(draw_current_step(COL_RED), draw_cursor_cycles);
+    if (redraw_trigs) {
+        PROF(draw_triggers(), draw_trigs_cycles);
+        redraw_trigs = false;
+    }
+    if (redraw_channels) {
+        PROF(draw_channels(), draw_btn_cycles);
+        redraw_channels = false;
+    }
+    if (redraw_pattern_buttons) {
+        PROF(draw_pattern_buttons(), draw_btn_cycles);
+        redraw_pattern_buttons = false;
+    }
+    if (redraw_bank_buttons) {
+        PROF(draw_bank_buttons(), draw_btn_cycles);
+        redraw_bank_buttons = false;
+    }
+    if (redraw_bpm) {
+        PROF(draw_bpm(), draw_btn_cycles);
+        redraw_bpm = false;
+    }
+    if (redraw_play_pause) {
+        PROF(draw_play(), draw_btn_cycles);
+        PROF(draw_stop(), draw_btn_cycles);
+        redraw_play_pause = false;
+    }
+    if (redraw_piano_note) {
+        PROF(draw_piano(), draw_piano_cycles);
+        // TODO: Draw the notes currently playing with a fade off animation for
+        // the first 3 channels.
+        TriggerNote *trig = get_current_trig();
+        PROF(draw_note(trig->note, COL_NOTE_PRESSED), draw_piano_cycles);
+        redraw_piano_note = false;
+    }
+    if (redraw_params) {
+        PROF(draw_parameters(), draw_param_cycles);
+        redraw_params = false;
+    }
+
+    // TODO: Make sure we are drawing the cursors properly.
+    // PROF(draw_trig_cursor(trig_selection_loc, COL_CURSOR), draw_cursor_cycles);
+    // PROF(draw_channel_cursor(channel_selection_loc, COL_GREY), draw_cursor_cycles);
+    // PROF(draw_pattern_cursor(pattern_selection_loc, COL_GREY), draw_cursor_cycles);
+
+    // PROF(draw_current_step(COL_RED), draw_cursor_cycles);
 }
 
 int
diff --git a/src/sequencer.c b/src/sequencer.c
index b689bf5..a560bcb 100644
--- a/src/sequencer.c
+++ b/src/sequencer.c
@@ -9,14 +9,14 @@
 
 void set_time(int bpm);
 
-bool redraw_pattern_buttons = false;
-bool redraw_play_pause = false;
-bool redraw_trigs = false;
-bool redraw_channels = false;
-bool redraw_bank_buttons = false;
-bool redraw_params = false;
-bool redraw_bpm = false;
-bool redraw_piano_note = false;
+bool redraw_pattern_buttons = true;
+bool redraw_play_pause = true;
+bool redraw_trigs = true;
+bool redraw_channels = true;
+bool redraw_bank_buttons = true;
+bool redraw_params = true;
+bool redraw_bpm = true;
+bool redraw_piano_note = true;
 
 void
 irq_timer(void) {
@@ -198,39 +198,30 @@ handle_channel_selection(void) {
                 patterns[pattern_selection_loc].ch4.active ^= 1;
             } break;
         }
-        draw_channels();
+        redraw_channels = true;
     }
     if (key_tap(KEY_RIGHT)) {
         trig_selection_loc = 0;
         param_selection_loc = 0;
         input_handler = handle_trigger_selection;
-        draw_channel_cursor(channel_selection_loc, COL_GREY);
-        draw_trig_cursor(trig_selection_loc, COL_CURSOR);
-        TriggerNote *trig = get_current_trig();
-        draw_note(trig->note, COL_NOTE_PRESSED);
-        draw_parameters();
+        redraw_piano_note = true;
+        redraw_params = true;
     } else if (key_tap(KEY_LEFT)) {
         input_handler = handle_pattern_selection;
-        draw_channel_cursor(channel_selection_loc, COL_GREY);
-        draw_pattern_cursor(pattern_selection_loc, COL_CURSOR);
     } else if (key_tap(KEY_UP)) {
-        draw_channel_cursor(channel_selection_loc, COL_BG);
         if (channel_selection_loc == 0) {
             channel_selection_loc = SEQ_N_CHANNELS - 1;
         } else {
             channel_selection_loc = MAX(channel_selection_loc - 1, 0);
         }
-        draw_channel_cursor(channel_selection_loc, COL_CURSOR);
-        draw_triggers();
+        redraw_trigs = true;
     } else if (key_tap(KEY_DOWN)) {
-        draw_channel_cursor(channel_selection_loc, COL_BG);
         if (channel_selection_loc == SEQ_N_CHANNELS - 1) {
             channel_selection_loc = 0;
         } else {
             channel_selection_loc = MIN(channel_selection_loc + 1, SEQ_N_CHANNELS);
         }
-        draw_channel_cursor(channel_selection_loc, COL_CURSOR);
-        draw_triggers();
+        redraw_trigs = true;
     }
 }
 
@@ -384,7 +375,6 @@ handle_pattern_selection(void) {
         }
     } else if (key_tap(KEY_DOWN)) {
         if (pattern_selection_loc < 7) {
-            draw_pattern_cursor(pattern_selection_loc, COL_BG);
             pattern_selection_loc = pattern_selection_loc + 1;
             redraw_channels = true;
             redraw_trigs = true;