Make canvas draggable

1 files changed, 98 insertions, 61 deletions

diff --git a/xnote.c b/xnote.c
index 0d7f546..06afd69 100644
--- a/xnote.c
+++ b/xnote.c
@@ -26,11 +26,12 @@ struct note {
 };
 
 enum event {
-	EVENT_IDLE,
+	EVENT_START,
 	EVENT_START_LINE,
 	EVENT_END_LINE,
 	EVENT_START_NOTE,
 	EVENT_MOUSE_MOVE,
+	EVENT_MOUSE_DRAG,
 };
 
 static struct line *lines = NULL;
@@ -45,9 +46,17 @@ static enum event *events = NULL;
 static size_t event_count = 0;
 static size_t event_cap = 0;
 
+static double canvas_x = 0;
+static double canvas_y = 0;
+
 static double cursor_x = 0;
 static double cursor_y = 0;
 
+static double drag_canvas_x = 0;
+static double drag_canvas_y = 0;
+static double drag_cursor_x = 0;
+static double drag_cursor_y = 0;
+
 static int window_width = 0;
 static int window_height = 0;
 
@@ -114,29 +123,42 @@ push_event(enum event event)
 	*slot = event;
 }
 
-static void
+static enum event
 pop_event(void)
 {
-	while (event_count > 0) {
-		event_count -= 1;
-		enum event event = events[event_count];
-		switch (event) {
+	event_count -= 1;
+	enum event event = events[event_count];
+	switch (event) {
+	case EVENT_START_LINE:
+		line_count -= 1;
+		free(lines[line_count].points);
+		break;
+	case EVENT_START_NOTE:
+		note_count -= 1;
+		free(notes[note_count].text);
+		break;
+	case EVENT_START:
+		event_count += 1;
+		break;
+	default:
+		break;
+	}
+	return event;
+}
+
+static void
+undo(void)
+{
+	while (1) {
+		switch (pop_event()) {
 		case EVENT_START_LINE:
-			line_count -= 1;
-			free(lines[line_count].points);
-			goto exit;
 		case EVENT_START_NOTE:
-			note_count -= 1;
-			free(notes[note_count].text);
-			goto exit;
-		case EVENT_IDLE:
-			event_count += 1;
+		case EVENT_START:
 			goto exit;
 		default:
-			break;
+			continue;
 		}
 	}
-
 exit:
 	shrink(&events, event_count, &event_cap, sizeof(enum event));
 }
@@ -172,8 +194,11 @@ mouse_move_cb(GLFWwindow *window, double x, double y)
 		}
 		struct point *point = append(&line->points,
 			&line->count, &line->cap, sizeof(struct point));
-		point->x = cursor_x;
-		point->y = cursor_y;
+		point->x = canvas_x + cursor_x;
+		point->y = canvas_y + cursor_y;
+	} else if (last_event() == EVENT_MOUSE_DRAG) {
+		canvas_x = drag_canvas_x - (cursor_x - drag_cursor_x);
+		canvas_y = drag_canvas_y - (cursor_y - drag_cursor_y);
 	} else if (last_event() != EVENT_MOUSE_MOVE) {
 		push_event(EVENT_MOUSE_MOVE);
 	}
@@ -182,24 +207,34 @@ mouse_move_cb(GLFWwindow *window, double x, double y)
 static void
 mouse_press_cb(GLFWwindow *window, int button, int action, int mods)
 {
-	if (button != GLFW_MOUSE_BUTTON_LEFT) return;
-
-	if (action == GLFW_PRESS) {
-		struct line *line = append(&lines,
-			&line_count, &line_cap, sizeof(struct line));
-		line->count = line->cap = 0;
-		line->points = NULL;
-		struct point *point = append(&line->points,
-			&line->count, &line->cap, sizeof(struct point));
-		point->x = cursor_x;
-		point->y = cursor_y;
-		push_event(EVENT_START_LINE);
-	} else if (action == GLFW_RELEASE) {
-		if (last_event() == EVENT_START_LINE) {
-			struct line *line = &lines[line_count-1];
-			shrink(&line->points, line->count,
-				&line->cap, sizeof(struct point));
-			push_event(EVENT_END_LINE);
+	if (button == GLFW_MOUSE_BUTTON_LEFT) {
+		if (action == GLFW_PRESS) {
+			struct line *line = append(&lines,
+				&line_count, &line_cap, sizeof(struct line));
+			line->count = line->cap = 0;
+			line->points = NULL;
+			struct point *point = append(&line->points,
+				&line->count, &line->cap, sizeof(struct point));
+			point->x = canvas_x + cursor_x;
+			point->y = canvas_y + cursor_y;
+			push_event(EVENT_START_LINE);
+		} else if (action == GLFW_RELEASE) {
+			if (last_event() == EVENT_START_LINE) {
+				struct line *line = &lines[line_count-1];
+				shrink(&line->points, line->count,
+					&line->cap, sizeof(struct point));
+				push_event(EVENT_END_LINE);
+			}
+		}
+	} else if (button == GLFW_MOUSE_BUTTON_RIGHT) {
+		if (action == GLFW_PRESS) {
+			drag_canvas_x = canvas_x;
+			drag_canvas_y = canvas_y;
+			drag_cursor_x = cursor_x;
+			drag_cursor_y = cursor_y;
+			push_event(EVENT_MOUSE_DRAG);
+		} else if (action == GLFW_RELEASE && last_event() == EVENT_MOUSE_DRAG) {
+			pop_event();
 		}
 	}
 }
@@ -207,26 +242,26 @@ mouse_press_cb(GLFWwindow *window, int button, int action, int mods)
 static void
 key_press_cb(GLFWwindow *window, int key, int scancode, int action, int mods)
 {
-	if (action != GLFW_PRESS) return;
-
-	if ((mods & GLFW_MOD_CONTROL) && !strcmp(glfwGetKeyName(key, scancode), "z")) {
-		if (event_count) pop_event();
-	} else if ((mods & GLFW_MOD_CONTROL) && !strcmp(glfwGetKeyName(key, scancode), "c")) {
-		for (size_t i = 0; i < line_count; i++)
-			free(lines[i].points);
-		line_count = 0;
-		for (size_t i = 0; i < note_count; i++)
-			free(notes[i].text);
-		note_count = 0;
-		event_count = 0;
-	} else if (key == GLFW_KEY_BACKSPACE && last_event() == EVENT_START_NOTE) {
-		if (note_count) {
-			struct note *note = &notes[note_count - 1];
-			if (note->len > 1) {
-				note->len -= 1;
-				shrink(&note->text, note->len, &note->cap, 1);
-			} else if (note->len == 1) {
-				pop_event();
+	if (action == GLFW_PRESS) {
+		if ((mods & GLFW_MOD_CONTROL) && !strcmp(glfwGetKeyName(key, scancode), "z")) {
+			if (event_count) undo();
+		} else if ((mods & GLFW_MOD_CONTROL) && !strcmp(glfwGetKeyName(key, scancode), "c")) {
+			for (size_t i = 0; i < line_count; i++)
+				free(lines[i].points);
+			line_count = 0;
+			for (size_t i = 0; i < note_count; i++)
+				free(notes[i].text);
+			note_count = 0;
+			event_count = 0;
+		} else if (key == GLFW_KEY_BACKSPACE && last_event() == EVENT_START_NOTE) {
+			if (note_count) {
+				struct note *note = &notes[note_count - 1];
+				if (note->len > 1) {
+					note->len -= 1;
+					shrink(&note->text, note->len, &note->cap, 1);
+				} else if (note->len == 1) {
+					pop_event();
+				}
 			}
 		}
 	}
@@ -242,8 +277,8 @@ key_char_cb(GLFWwindow *window, unsigned int codepoint)
 		struct note *note = append(&notes, &note_count, &note_cap, sizeof(struct note));
 		note->text = NULL;
 		note->len = note->cap = 0;
-		note->x = cursor_x;
-		note->y = cursor_y;
+		note->x = canvas_x + cursor_x;
+		note->y = canvas_y + cursor_y;
 		push_event(EVENT_START_NOTE);
 	}
 
@@ -318,7 +353,7 @@ main(void)
 
 	window_resize_cb(window, window_width, window_height);
 
-	push_event(EVENT_IDLE);
+	push_event(EVENT_START);
 
 	FT_Library freetype;
 	FT_Face face;
@@ -354,14 +389,16 @@ main(void)
 
 		for (size_t i = 0; i < note_count; i++) {
 			struct note *note = &notes[i];
-			draw_text(note->text, note->len, note->x, note->y);
+			draw_text(note->text, note->len,
+				note->x - canvas_x, note->y - canvas_y);
 		}
 
 		for (size_t i = 0; i < line_count; i++) {
 			struct line *line = &lines[i];
 			glBegin(GL_LINE_STRIP);
 			for (size_t k = 0; k < line->count; k++)
-				glVertex2f(line->points[k].x, line->points[k].y);
+				glVertex2f(line->points[k].x - canvas_x,
+					line->points[k].y - canvas_y);
 			glEnd();
 		}