GUAC-803: Update rendering of scrollbar as terminal display is scrolled or resized. Position and scale inner box of scrollbar appropriately.

src/terminal/scrollbar.c

@@ -31,7 +31,7 @@
 #include <stdlib.h>
 
 guac_terminal_scrollbar* guac_terminal_scrollbar_alloc(guac_client* client,
-        const guac_layer* parent, int parent_width, int parent_height) {
+        const guac_layer* parent, int parent_width, int parent_height, int visible_area) {
 
     /* Allocate scrollbar */
     guac_terminal_scrollbar* scrollbar =
@@ -49,6 +49,7 @@ guac_terminal_scrollbar* guac_terminal_scrollbar_alloc(guac_client* client,
     scrollbar->parent        = parent;
     scrollbar->parent_width  = 0;
     scrollbar->parent_height = 0;
+    scrollbar->visible_area  = 0;
 
     /* Allocate and init layers */
     scrollbar->container = guac_client_alloc_layer(client);
@@ -56,7 +57,7 @@ guac_terminal_scrollbar* guac_terminal_scrollbar_alloc(guac_client* client,
 
     /* Reposition and resize to fit parent */
     guac_terminal_scrollbar_parent_resized(scrollbar,
-            parent_width, parent_height);
+            parent_width, parent_height, visible_area);
 
     return scrollbar;
 
@@ -73,41 +74,37 @@ void guac_terminal_scrollbar_free(guac_terminal_scrollbar* scrollbar) {
 
 }
 
-void guac_terminal_scrollbar_set_bounds(guac_terminal_scrollbar* scrollbar,
+/**
-        int min, int max) {
+ * Updates the position and size of the scrollbar inner box relative to the
-    /* STUB */
+ * current scrollbar value, bounds, and parent layer dimensions.
-}
+ *
-
+ * @param scrollbar
-void guac_terminal_scrollbar_set_value(guac_terminal_scrollbar* scrollbar,
+ *     The scrollbar whose inner box should be updated.
-        int value) {
+ */
-    /* STUB */
+static void __update_box(guac_terminal_scrollbar* scrollbar) {
-}
-
-void guac_terminal_scrollbar_parent_resized(guac_terminal_scrollbar* scrollbar,
-        int parent_width, int parent_height) {
 
     guac_socket* socket = scrollbar->client->socket;
 
-    /* Calculate container position and dimensions */
+    /* Skip if no scrolling region at all */
-    int container_x      = parent_width - GUAC_TERMINAL_SCROLLBAR_WIDTH;
+    if (scrollbar->min >= scrollbar->max)
-    int container_y      = 0;
+        return;
-    int container_width  = GUAC_TERMINAL_SCROLLBAR_WIDTH;
+
-    int container_height = parent_height;
+    int region_size = scrollbar->max - scrollbar->min;
+
+    /* Calculate box dimensions */
+    int box_width  = GUAC_TERMINAL_SCROLLBAR_WIDTH - GUAC_TERMINAL_SCROLLBAR_PADDING*2;
+    int box_height = GUAC_TERMINAL_SCROLLBAR_MIN_HEIGHT;
+
+    /* Size box relative to visible area */
+    int padded_container_height = (scrollbar->parent_height - GUAC_TERMINAL_SCROLLBAR_PADDING*2);
+    int proportional_height = padded_container_height * scrollbar->visible_area / (region_size + scrollbar->visible_area);
+    if (proportional_height > box_height)
+        box_height = proportional_height;
 
     /* Calculate box position and dimensions */
     int box_x = GUAC_TERMINAL_SCROLLBAR_PADDING;
-    int box_y      = GUAC_TERMINAL_SCROLLBAR_PADDING;
+    int box_y = GUAC_TERMINAL_SCROLLBAR_PADDING
-    int box_width  = GUAC_TERMINAL_SCROLLBAR_WIDTH - GUAC_TERMINAL_SCROLLBAR_PADDING*2;
+              + (padded_container_height - box_height) * (scrollbar->value - scrollbar->min) / region_size;
-    int box_height = 64; /* STUB */
-
-    /* Reposition container relative to parent dimensions */
-    guac_protocol_send_move(socket,
-            scrollbar->container, scrollbar->parent,
-            container_x, container_y, 0);
-
-    /* Resize to fit within parent */
-    guac_protocol_send_size(socket, scrollbar->container,
-            container_width, container_height);
 
     /* Reposition box relative to container and current value */
     guac_protocol_send_move(socket,
@@ -122,9 +119,70 @@ void guac_terminal_scrollbar_parent_resized(guac_terminal_scrollbar* scrollbar,
     guac_protocol_send_rect(socket, scrollbar->box, 0, 0, box_width, box_height);
     guac_protocol_send_cfill(socket, GUAC_COMP_SRC, scrollbar->box, 0xFF, 0xFF, 0xFF, 0x80);
 
-    /* Assign new dimensions */
+}
-    scrollbar->parent_width  = parent_width;
+
-    scrollbar->parent_height = parent_height;
+void guac_terminal_scrollbar_set_bounds(guac_terminal_scrollbar* scrollbar,
+        int min, int max) {
+
+    /* Fit value within bounds */
+    if (scrollbar->value > max)
+        scrollbar->value = max;
+    else if (scrollbar->value < min)
+        scrollbar->value = min;
+
+    /* Update bounds */
+    scrollbar->min = min;
+    scrollbar->max = max;
+
+    /* Update box position and size */
+    __update_box(scrollbar);
+
+}
+
+void guac_terminal_scrollbar_set_value(guac_terminal_scrollbar* scrollbar,
+        int value) {
+
+    /* Fit value within bounds */
+    if (value > scrollbar->max)
+        value = scrollbar->max;
+    else if (value < scrollbar->min)
+        value = scrollbar->min;
+
+    /* Update value */
+    scrollbar->value = value;
+
+    /* Update box position and size */
+    __update_box(scrollbar);
+
+}
+
+void guac_terminal_scrollbar_parent_resized(guac_terminal_scrollbar* scrollbar,
+        int parent_width, int parent_height, int visible_area) {
+
+    guac_socket* socket = scrollbar->client->socket;
+
+    /* Calculate container position and dimensions */
+    int container_x      = parent_width - GUAC_TERMINAL_SCROLLBAR_WIDTH;
+    int container_y      = 0;
+    int container_width  = GUAC_TERMINAL_SCROLLBAR_WIDTH;
+    int container_height = parent_height;
+
+    /* Reposition container relative to parent dimensions */
+    guac_protocol_send_move(socket,
+            scrollbar->container, scrollbar->parent,
+            container_x, container_y, 0);
+
+    /* Resize to fit within parent */
+    guac_protocol_send_size(socket, scrollbar->container,
+            container_width, container_height);
+
+    /* Assign new dimensions */
+    scrollbar->parent_width  = parent_width;
+    scrollbar->parent_height = parent_height;
+    scrollbar->visible_area  = visible_area;
+
+    /* Update box position and size */
+    __update_box(scrollbar);
 
 }
 

src/terminal/scrollbar.h

@@ -91,6 +91,11 @@ typedef struct guac_terminal_scrollbar {
      */
     int max;
 
+    /**
+     * The size of the visible area, in the same units as min and max.
+     */
+    int visible_area;
+
     /**
      * The current scroll value.
      */
@@ -119,11 +124,17 @@ typedef struct guac_terminal_scrollbar {
  * @param parent_height
  *     The height of the parent layer, in pixels.
  *
+ * @param visible_area
+ *     The amount of scrollable data that can be shown within the parent layer
+ *     at any given time. This value uses the same units as min, max, and the
+ *     current scroll value.
+ *
  * @return
  *     A newly allocated scrollbar.
  */
 guac_terminal_scrollbar* guac_terminal_scrollbar_alloc(guac_client* client,
-        const guac_layer* parent, int parent_width, int parent_height);
+        const guac_layer* parent, int parent_width, int parent_height,
+        int visible_area);
 
 /**
  * Frees the given scrollbar.
@@ -186,8 +197,13 @@ void guac_terminal_scrollbar_set_value(guac_terminal_scrollbar* scrollbar,
  *
  * @param parent_height
  *     The new height of the parent layer, in pixels.
+ *
+ * @param visible_area
+ *     The amount of scrollable data that can be shown within the parent layer
+ *     at any given time. This value uses the same units as min, max, and the
+ *     current scroll value.
  */
 void guac_terminal_scrollbar_parent_resized(guac_terminal_scrollbar* scrollbar,
-        int parent_width, int parent_height);
+        int parent_width, int parent_height, int visible_area);
 
 #endif

src/terminal/terminal.c

@@ -167,6 +167,10 @@ void guac_terminal_reset(guac_terminal* term) {
     term->scroll_end = term->term_height - 1;
     term->scroll_offset = 0;
 
+    /* Reset scrollbar bounds */
+    guac_terminal_scrollbar_set_bounds(term->scrollbar, term->term_height - term->buffer->length, 0);
+    guac_terminal_scrollbar_set_value(term->scrollbar, -term->scroll_offset);
+
     /* Reset flags */
     term->text_selected = false;
     term->application_cursor_keys = false;
@@ -251,6 +255,10 @@ guac_terminal* guac_terminal_create(guac_client* client,
     guac_terminal_display_resize(term->display,
             term->term_width, term->term_height);
 
+    /* Allocate scrollbar */
+    term->scrollbar = guac_terminal_scrollbar_alloc(term->client,
+            GUAC_DEFAULT_LAYER, width, height, term->term_height);
+
     /* Init terminal */
     guac_terminal_reset(term);
 
@@ -269,10 +277,6 @@ guac_terminal* guac_terminal_create(guac_client* client,
     /* Allocate clipboard */
     term->clipboard = guac_common_clipboard_alloc(GUAC_TERMINAL_CLIPBOARD_MAX_LENGTH);
 
-    /* Allocate scrollbar */
-    term->scrollbar = guac_terminal_scrollbar_alloc(term->client,
-            GUAC_DEFAULT_LAYER, width, height);
-
     return term;
 
 }
@@ -524,6 +528,9 @@ int guac_terminal_scroll_up(guac_terminal* term,
         if (term->buffer->length > term->buffer->available)
             term->buffer->length = term->buffer->available;
 
+        /* Reset scrollbar bounds */
+        guac_terminal_scrollbar_set_bounds(term->scrollbar, term->term_height - term->buffer->length, 0);
+
         /* Update cursor location if within region */
         if (term->visible_cursor_row >= start_row &&
             term->visible_cursor_row <= end_row)
@@ -639,6 +646,7 @@ void guac_terminal_scroll_display_down(guac_terminal* terminal,
 
     /* Advance by scroll amount */
     terminal->scroll_offset -= scroll_amount;
+    guac_terminal_scrollbar_set_value(terminal->scrollbar, -terminal->scroll_offset);
 
     /* Get row range */
     end_row   = terminal->term_height - terminal->scroll_offset - 1;
@@ -703,6 +711,7 @@ void guac_terminal_scroll_display_up(guac_terminal* terminal,
 
     /* Advance by scroll amount */
     terminal->scroll_offset += scroll_amount;
+    guac_terminal_scrollbar_set_value(terminal->scrollbar, -terminal->scroll_offset);
 
     /* Get row range */
     start_row = -terminal->scroll_offset;
@@ -1080,6 +1089,7 @@ static void __guac_terminal_resize(guac_terminal* term, int width, int height) {
             if (term->scroll_offset >= shift_amount) {
 
                 term->scroll_offset -= shift_amount;
+                guac_terminal_scrollbar_set_value(term->scrollbar, -term->scroll_offset);
 
                 /* Draw characters from scroll at bottom */
                 __guac_terminal_redraw_rect(term, term->term_height, 0, term->term_height + shift_amount - 1, width-1);
@@ -1095,6 +1105,7 @@ static void __guac_terminal_resize(guac_terminal* term, int width, int height) {
                 /* Update shift_amount and scroll based on new rows */
                 shift_amount -= term->scroll_offset;
                 term->scroll_offset = 0;
+                guac_terminal_scrollbar_set_value(term->scrollbar, -term->scroll_offset);
 
                 /* If anything remains, move screen as necessary */
                 if (shift_amount > 0) {
@@ -1139,7 +1150,8 @@ int guac_terminal_resize(guac_terminal* terminal, int width, int height) {
     guac_protocol_send_size(socket, GUAC_DEFAULT_LAYER, width, height);
 
     /* Notify scrollbar of resize */
-    guac_terminal_scrollbar_parent_resized(terminal->scrollbar, width, height);
+    guac_terminal_scrollbar_parent_resized(terminal->scrollbar, width, height, rows);
+    guac_terminal_scrollbar_set_bounds(terminal->scrollbar, rows - terminal->buffer->length, 0);
 
     /* Resize terminal if row/column dimensions have changed */
     if (columns != terminal->term_width || rows != terminal->term_height) {