[SPACE] + mouse drag
Hold down the spacebar, then click with left mouse button on canvas and, holding the left button down, drag the canvas in the desired position.
Zooming at current cursor position
Mouse Wheel or [+/-] keys
'+' key: zoom in
'-' key: zoom out
Both the wheel zoom and the keyboard zoom, work relatively to the current cursor position, so if you have your cursor over a detail of the image, and you zoom in or out, the detail will still stay under the cursor.
Zooming at center of the drawing area
[CTRL] + [ALT] + [MOUSE LEFT] + vertical mouse movement
[CTRL] + mouse drag
Hold down the [CTRL] key, then click with left mouse button on the canvas and, still holding the button down, move the mouse around the circular HUD that appears at the center of the canvas.
Reset canvas position
To fit the cavas on the screen, you can use the 'c' key (which stands for "center canvas").
The behaviour of this command varies depending on the status of the GUI. When the GUI is hidden the canvas will fit the entire window area, on the other case it will not cover the whole area, in order to not overlap too much with GUI widgets.
The color selector is normally shown on the right side of the application.
Alternatively, if you press and hold down the mouse right button, the color selector will appear at current cursor position, toghether with the brush size slider and a brush preview, as you can see in the image above.Holding the [SHIFT] modifier you will be able to constrain the curson movements only horizontally or vertically, in order to modify brigthness or saturation independently. Vertical movements will modify color brigthness. Horizontal movements will modify color saturation.
Hotkey to quick change brush size
[CTRL] + [SPACE] + drag mouse horizontally
Image/drawing process buttons
WARNING! In order to preserve the whole multi-layered structure of the image, you have to choose the ".spf" file format, that also stores informations about each layer's opacity and visibility flag. Saving in the other file formats will result in a "flattened" image, where all the layers are merged together.
On the lower right corner of the application, you can see a miniatures for each layer in the image.
The current layer is the one highlighted with a cyan border. Brush strokes will be applied only to the current layer. To select a layer as the current one, just left click on it.
A small square on the left of each miniature will inform you on the visibility status of each layer. When the layer is visible the square is cyan, on the opposite case a grey square indicates that the layer is hidden. To toggle the visibility status of a layer, just doubleclick on it. An alternative way to toggle layer visibility status is to press 'h' key, the status change will be applied to the current layer.
You can change layer ordering by just drag and drop layers from one position to another. A small white triangle shown while dragging a layer, will tell you where the layer would be positioned if you realease the mouse button.
You can change layer opacity using the layer opacity slider shown on the bottom of the miniatures. The opacity changes will affect only the current layer.