From 8461f5dec71f5d63d8ffba2ae1bb73ce2e74a000 Mon Sep 17 00:00:00 2001
From: Leo Tenenbaum <pommicket@gmail.com>
Date: Wed, 25 Nov 2020 19:50:58 -0500
Subject: scrolling

---
 buffer.c | 17 ++++++++++++++++-
 main.c   | 44 ++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/buffer.c b/buffer.c
index 7fea0d3..cd6c353 100644
--- a/buffer.c
+++ b/buffer.c
@@ -22,6 +22,7 @@ typedef struct {
 
 typedef struct {
 	u32 nblocks; // number of text blocks
+	double scroll_x, scroll_y; // number of characters scrolled in the x/y direction
 	TextBlock *blocks;
 } TextBuffer;
 
@@ -117,18 +118,27 @@ void text_buffer_free(TextBuffer *buffer) {
 	free(blocks);
 }
 
+void text_buffer_scroll(TextBuffer *buffer, double dx, double dy) {
+	buffer->scroll_x += dx;
+	buffer->scroll_y += dy;
+}
+
 // Render the text buffer in the given rectangle
 void text_buffer_render(TextBuffer *buffer, Font *font, float x1, float y1, float x2, float y2) {
 	mbstate_t mbstate = {0};
 	uint nblocks = buffer->nblocks;
 	TextBlock *blocks = buffer->blocks;
-	glBegin(GL_LINE_LOOP);
+	float char_height = text_font_char_height(font);
+	glColor3f(0.5f,0.5f,0.5f);
+	glBegin(GL_LINE_STRIP);
 	glVertex2f(x1,y1);
 	glVertex2f(x1,y2);
 	glVertex2f(x2,y2);
 	glVertex2f(x2,y1);
+	glVertex2f(x1-1,y1);
 	glEnd();
 
+	glColor3f(1,1,1);
 	text_chars_begin(font);
 	TextRenderState text_state = {
 		.x = x1, .y = y1 + text_font_char_height(font),
@@ -136,6 +146,10 @@ void text_buffer_render(TextBuffer *buffer, Font *font, float x1, float y1, floa
 		.max_x = x2, .max_y = y2
 	};
 
+	// @TODO: make this better (we should figure out where to start rendering, etc.)
+	text_state.x -= (float)buffer->scroll_x * char_height;
+	text_state.y -= (float)buffer->scroll_y * char_height;
+
 	for (uint block_idx = 0; block_idx < nblocks; ++block_idx) {
 		TextBlock *block = &blocks[block_idx];
 		char *p = block->contents, *end = p + block->len;
@@ -177,3 +191,4 @@ void text_buffer_render(TextBuffer *buffer, Font *font, float x1, float y1, floa
 	}
 	text_chars_end(font);
 }
+
diff --git a/main.c b/main.c
index c655d42..feb526a 100644
--- a/main.c
+++ b/main.c
@@ -1,4 +1,3 @@
-
 #include "base.h"
 no_warn_start
 #if _WIN32
@@ -36,6 +35,7 @@ INT WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
 int main(void) {
 #endif
 	setlocale(LC_ALL, ""); // allow unicode
+	SDL_SetHint(SDL_HINT_NO_SIGNAL_HANDLERS, "1"); // if this program is sent a SIGTERM/SIGINT, don't turn it into a quit event 
 	if (SDL_Init(SDL_INIT_VIDEO|SDL_INIT_TIMER) < 0)
 		die("%s", SDL_GetError());
 
@@ -43,7 +43,7 @@ int main(void) {
 		SDL_WINDOWPOS_UNDEFINED, 1280, 720, SDL_WINDOW_SHOWN|SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
 	if (!window)
 		die("%s", SDL_GetError());
-
+		
 	{ // set icon
 		SDL_Surface *icon = SDL_LoadBMP("assets/icon.bmp");
 		SDL_SetWindowIcon(window, icon);
@@ -77,16 +77,54 @@ int main(void) {
 	}
 
 
+	Uint32 time_at_last_frame = SDL_GetTicks();
+
 	while (!quit) {
 		SDL_Event event;
+			
+
 		while (SDL_PollEvent(&event)) {
 			switch (event.type) {
 			case SDL_QUIT:
 				quit = true;
 				break;
+			case SDL_MOUSEWHEEL: {
+				// scroll with mouse wheel
+				Sint32 dx = event.wheel.x, dy = -event.wheel.y;
+				double scroll_speed = 2.5;
+				text_buffer_scroll(&text_buffer, dx * scroll_speed, dy * scroll_speed);
+			} break;
 			}
 		}
 
+		Uint8 const *keyboard_state = SDL_GetKeyboardState(NULL);
+		bool control_key_down = keyboard_state[SDL_SCANCODE_LCTRL] || keyboard_state[SDL_SCANCODE_RCTRL];
+
+		double frame_dt;
+		{
+			Uint32 time_this_frame = SDL_GetTicks();
+			frame_dt = 0.001 * (time_this_frame - time_at_last_frame);
+			time_at_last_frame = time_this_frame;
+		}
+
+		if (control_key_down) {
+			// control + arrow keys to scroll
+			double scroll_speed = 20.0;
+			double scroll_amount = scroll_speed * frame_dt;
+			if (keyboard_state[SDL_SCANCODE_UP])
+				text_buffer_scroll(&text_buffer, 0, -scroll_amount);
+			if (keyboard_state[SDL_SCANCODE_DOWN])
+				text_buffer_scroll(&text_buffer, 0, +scroll_amount);
+			// @TODO: get this to work
+			#if 0
+			if (keyboard_state[SDL_SCANCODE_LEFT])
+				text_buffer_scroll(&text_buffer, -scroll_amount, 0);
+			if (keyboard_state[SDL_SCANCODE_RIGHT])
+				text_buffer_scroll(&text_buffer, +scroll_amount, 0);
+			#endif
+		}
+			
+
 		int window_width = 0, window_height = 0;
 		SDL_GetWindowSize(window, &window_width, &window_height);
 		float window_widthf = (float)window_width, window_heightf = (float)window_height;
@@ -102,8 +140,6 @@ int main(void) {
 		glClearColor(0, 0, 0, 1);
 		glClear(GL_COLOR_BUFFER_BIT);
 
-		glColor3f(1,1,1);
-
 		{
 			float x1 = 50, y1 = 50, x2 = window_widthf-50, y2 = window_heightf-50;
 			text_buffer_render(&text_buffer, font, x1, y1, x2, y2);
-- 
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