The `level.Canvas` is a widget that holds onto its Palette and Grid and
has interactions to allow scrolling and editing the grid using the
swatches available on the palette.
Thus all of the logic in the Editor Mode for drawing directly onto the
root SDL surface are now handled inside a level.Canvas instance.
The `level.Canvas` widget has the following properties:
* Like any widget it has an X,Y position and a width/height.
* It has a Scroll position to control which slice of its drawing will be
visible inside its bounding box.
* It supports levels having negative coordinates for their pixels. It
doesn't care. The default Scroll position is (0,0) at the top left
corner of the widget but you can scroll into the negatives and see the
negative pixels.
* Keyboard keys will scroll the viewport inside the canvas.
* The canvas draws only the pixels that are visible inside its bounding
box.
This feature will eventually pave the way toward:
* Doodads being dropped on top of your map, each Doodad being its own
Canvas widget.
* Using drawings as button icons for the user interface, as the Canvas
is a normal widget.
* Added a "menu toolbar" to the top of the Edit Mode with useful buttons
that work: New Level, New Doodad (same thing), Save, Save as, Open.
* Added ability for the dev console to prompt the user for a question,
which opens the console automatically. "Save", "Save as" and "Load"
ask for their filenames this way.
* Started groundwork for theming the app. The palette window is a light
brown with an orange title bar, the Menu Toolbar has a black
background, etc.
* Added support for multiple fonts instead of just monospace. DejaVu
Sans (normal and bold) are used now for most labels and window titles,
respectively. The dev console uses DejaVu Sans Mono as before.
* Update ui.Label to accept PadX and PadY separately instead of only
having the Padding option which did both.
* Improvements to Frame packing algorithm.
* Set the SDL draw mode to BLEND so we can use alpha colors properly,
so now the dev console is semi-translucent.
* Added `BoxSize()` to Widget that reports the full box size including
borders and margin.
* The Frame uses the `BoxSize()` of widgets to position them.
Reintroduces some padding issues (boxes on the GUI Test stick out of
bounds a bit) but is on the right track.
* Renamed `Padding` to `Margin` on the Widget object, since the Margin
is taken into consideration along with Outline and Border in computing
the widget's BoxSize.
* Restructured the Label widget to take a Text or TextVariable property
and the font settings (render.Text) are in a new `Font` property.
CheckButton is a generic component based on Button that additionally
takes a *bool variable to manage. When the CheckButton is clicked or
unclicked, it will toggle the bool var and its border style will "stick"
in or out depending on the state.
Checkbox is a Frame widget that wraps a CheckButton and another child
widget, such as a Label. Interacting with the child widget will forward
all of its mouse events to the CheckButton, so that the Label could be
clicked instead of just the box itself.
* Frame.Pack() now supports Fill and Expand and works like Tk.
* The GUITest Scene now draws a large window with two fixed side panels,
an expanding body panel, and a fixed footer with buttons. The panels
are filled with other buttons and widgets showing off the Frame
packing.
