[gegl] bin: add lua code for image viewer mode

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 17fe617360cf06a5e02682f0b7a4e5007bd37b82
Author: Øyvind Kolås <pippin gimp org>
Date:   Tue Feb 19 21:57:13 2019 +0100

    bin: add lua code for image viewer mode
    
    Mostly complete reimplementation of C version of image viewer code, including
    gesture pan/zoom as well as mouse / scroll event pan/zoom.

 bin/lua/viewer.lua | 242 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 242 insertions(+)
---
diff --git a/bin/lua/viewer.lua b/bin/lua/viewer.lua
new file mode 100644
index 000000000..427b45457
--- /dev/null
+++ b/bin/lua/viewer.lua
@@ -0,0 +1,242 @@
+-- mrg ui for image viewer mode of gegl ui
+
+-- todo : implement thumb-bar of previous/next image
+--        timeout for showing of controls
+
+
+cr:new_path()
+cr:rectangle(0,0,mrg:width(),mrg:height())
+
+if zoom_pinch_coord == nil then
+  zoom_pinch_coord = {{},{},{},{}}
+end
+
+mrg:listen(Mrg.DRAG, function(event)
+  if event.type == Mrg.DRAG_PRESS then
+
+    if event.device_no == 5 then -- 5 = second finger
+      zoom_pinch_coord[2].x = event.x;
+      zoom_pinch_coord[2].y = event.y;
+
+      zoom_pinch_coord[3].x = zoom_pinch_coord[1].x;
+      zoom_pinch_coord[3].y = zoom_pinch_coord[1].y;
+      zoom_pinch_coord[4].x = zoom_pinch_coord[2].x;
+      zoom_pinch_coord[4].y = zoom_pinch_coord[2].y;
+
+      zoom_pinch = 1
+      orig_zoom = o.scale
+    elseif event.device_no == 1 or event.device_no == 4 then -- mouse or first finger
+      zoom_pinch_coord[1].x = event.x;
+      zoom_pinch_coord[1].y = event.y;
+
+    end
+  elseif event.type == Mrg.DRAG_MOTION then
+    if event.device_no == 1 or event.device_no == 4 then
+      zoom_pinch_coord[1].x = event.x;
+      zoom_pinch_coord[1].y = event.y;
+    end
+    if event.device_no == 5 then
+      zoom_pinch_coord[2].x = event.x;
+      zoom_pinch_coord[2].y = event.y;
+    end
+
+    if zoom_pinch ~= nil then
+      local orig_dist = ffi.C.hypotf (zoom_pinch_coord[3].x - zoom_pinch_coord[2].x ,
+                                      zoom_pinch_coord[3].y - zoom_pinch_coord[2].y );
+      local dist = ffi.C.hypotf (zoom_pinch_coord[1].x - zoom_pinch_coord[2].x ,
+                                 zoom_pinch_coord[1].y - zoom_pinch_coord[2].y);
+      local x, y;
+      local screen_cx = (zoom_pinch_coord[1].x + zoom_pinch_coord[2].x)/2;
+      local screen_cy = (zoom_pinch_coord[1].y + zoom_pinch_coord[2].y)/2;
+
+      local x = (o.u + screen_cx) / o.scale
+      local y = (o.v + screen_cy) / o.scale
+
+      o.scale = orig_zoom * dist / orig_dist;
+      o.u = x * o.scale - screen_cx;
+      o.v = y * o.scale - screen_cy;
+
+      o.u = o.u - (event.delta_x )/2
+      o.v = o.v - (event.delta_y )/2
+      o.is_fit = 0;
+    else
+      o.u = o.u - event.delta_x
+      o.v = o.v - event.delta_y
+    end
+  elseif event.type == Mrg.DRAG_RELEASE then
+    zoom_pinch = nil
+  end
+  event:stop_propagate()
+end)
+
+
+
+
+mrg:listen(Mrg.MOTION, function(event)
+  o.show_controls = 1
+  end)
+
+mrg:listen(Mrg.SCROLL, function(event)
+  local factor = 1.05
+  local x = (o.u + event.device_x) / o.scale
+  local y = (o.v + event.device_y) / o.scale
+
+  if event.scroll_direction == Mrg.SCROLL_DIRECTION_DOWN then
+    o.scale = o.scale * factor
+  elseif event.scroll_direction == Mrg.SCROLL_DIRECTION_UP then
+    o.scale = o.scale / factor
+  end
+
+  o.u = x * o.scale - event.device_x
+  o.v = y * o.scale - event.device_y
+  o.is_fit = 0
+  mrg:queue_draw(nil)
+end
+)
+
+function draw_grid(x,y,w,h)
+  cr:new_path()
+  cr:rectangle (0.00 *w + x, 0.00 * h + y, 0.33 * w, 0.33 * h)
+  cr:rectangle (0.66 *w + x, 0.00 * h + y, 0.33 * w, 0.33 * h)
+  cr:rectangle (0.00 *w + x, 0.66 * h + y, 0.33 * w, 0.33 * h)
+  cr:rectangle (0.66 *w + x, 0.66 * h + y, 0.33 * w, 0.33 * h)
+end
+
+function draw_back(x,y,w,h)
+  cr:new_path ();
+  cr:new_path ();
+  cr:move_to (x+0.9*w, y+0.1*h);
+  cr:line_to (x+0.9*w, y+0.9*h);
+  cr:line_to (x+0.1*w, y+0.5*h);
+end
+
+function draw_forward(x,y,w,h)
+  cr:new_path ();
+  cr:move_to (x+0.1*w, y+0.1*h);
+  cr:line_to (x+0.1*w, y+0.9*h);
+  cr:line_to (x+0.9*w, y+0.5*h);
+end
+
+function draw_edit(x,y,w,h)
+  cr:new_path ();
+  cr:arc (x+0.5*w, y+0.5*h, h * .4, 0.0, 3.1415 * 2);
+end
+
+function contrasty_stroke()
+  local x0 = 6.0
+  local y0 = 6.0;
+  local x1 = 4.0
+  local y1 = 4.0;
+
+  x0, y0 = cr:device_to_user_distance (x0, y0)
+  x1, y1 = cr:device_to_user_distance (x1, y1)
+  cr:set_source_rgba (0,0,0,0.5);
+  cr:set_line_width (y0);
+  cr:stroke_preserve ()
+  cr:set_source_rgba (1,1,1,0.5);
+  cr:set_line_width (y1);
+  cr:stroke ();
+end
+
+-- ui_viewer
+
+cr:save()
+cr:rectangle(0,0,mrg:width(),mrg:height())
+
+local width = mrg:width()
+local height = mrg:height()
+
+draw_grid(height* 0.1/4, height * 0.1/4, height * 0.1, height *0.1)
+
+if o.show_controls ~= 0 then
+  contrasty_stroke()
+else
+  cr:new_path()
+end
+
+cr:rectangle (0, 0, height * 0.15, height * 0.15);
+
+if o.show_controls ~= 0 then
+  cr:set_source_rgba (1,1,1,.1);
+  cr:fill_preserve ();
+end
+
+mrg:listen(Mrg.PRESS, function(event) ffi.C.argvs_eval('parent') end)
+
+draw_back (height * .1 / 4, height * .5, height * .1, height *.1);
+cr:close_path ();
+
+if o.show_controls ~= 0 then
+  contrasty_stroke ();
+else
+  cr:new_path ();
+end
+
+cr:rectangle (0, height * .3, height * .15, height *.7);
+
+if o.show_controls ~= 0 then
+  cr:set_source_rgba (1,1,1,.1);
+  cr:fill_preserve ();
+end
+
+mrg:listen(Mrg.PRESS, function(event) ffi.C.argvs_eval('prev') end)
+cr:new_path ();
+
+draw_forward (width - height * .12, height * .5, height * .1, height *.1);
+cr:close_path ();
+
+if o.show_controls ~= 0 then
+  contrasty_stroke ();
+else
+  cr:new_path ();
+end
+
+cr:rectangle (width - height * .15, height * .3, height * .15, height *.7);
+
+if o.show_controls ~= 0 then
+  cr:set_source_rgba (1,1,1,.1);
+  cr:fill_preserve ();
+end
+
+mrg:listen(Mrg.PRESS, function(event) ffi.C.argvs_eval('next') end)
+
+
+draw_edit (width - height * .15, height * .0, height * .15, height *.15);
+if o.show_controls ~= 0 then
+  contrasty_stroke ();
+else
+  cr:new_path ();
+end
+
+cr:rectangle (width - height * .15, height * .0, height * .15, height *.15);
+if o.show_controls ~= 0 then
+ cr:set_source_rgba (1,1,1,.1);
+ cr:fill_preserve ();
+end
+mrg:listen(Mrg.PRESS, function(event) ffi.C.argvs_eval('toggle editing') end)
+cr:new_path ();
+
+
+mrg:add_binding("page-up", NULL, "previous image",
+  function() ffi.C.argvs_val ("prev") end)
+
+mrg:add_binding("page-down", NULL, "next image",
+  function() ffi.C.argvs_val ("next") end)
+
+mrg:add_binding("alt-right", NULL, "next image",
+  function() ffi.C.argvs_val ("next") end)
+
+mrg:add_binding("alt-left", NULL, "rev image",
+  function() ffi.C.argvs_val ("prev") end)
+
+mrg:add_binding("control-s", NULL, "toggle slideshow",
+  function() ffi.C.argvs_val ("toggle slideshow") end)
+
+mrg:add_binding("control-m", NULL, "toggle mipmap",
+  function() ffi.C.argvs_val ("toggle mipmap") end)
+
+mrg:add_binding("control-y", NULL, "toggle display profile",
+  function() ffi.C.argvs_val ("toggle colormanaged-display") end)
+
+mrg:add_binding("control-delete", NULL, "discard",
+  function() ffi.C.argvs_val ("discard") end)