<DataType> void paint() {
Canvas c = Canvas.get();
CellStamp<DataType> stamp;
int y = 0;
for (int i = 0; i < model.getRowCount(Section.SCROLLABLE); i++) {
RowAddress address = viewport.createAddress(i, Section.SCROLLABLE);
@SuppressWarnings("unchecked")
DataType datum = (DataType) model.get(address);
stamp = stampFactory.getStamp(address, datum);
Axis.Span stampSpan = new Axis.Span(Axis.V, y, stamp.getSpan(Axis.V, datum));
if (viewport
.getCellPainter()
.isRowVisible(stampSpan, RowVisibilityType.ACKNOWLEDGE_PARTIAL)) {
// WIP: BG such as highlight needs to paint outside this inset I just pushed
c.pushBounds(
ListModelPainter.CELL_TEXT_INSET, y, viewport.getBounds().width, stampSpan.span);
stamp.paint(c, address, datum);
c.popBounds();
}
y += stampSpan.span;
}
}
@Override
@SuppressWarnings("unchecked")
public void paint() {
/**
* @JTourBusStop 2, Stack-based properties for java.awt.Graphics, Obtaining the canvas
* automatically creates a stack frame:
*
* <p>Client code need not be concerned about when to create a stack frame for the Canvas. The
* only way to get a Canvas instance is by calling Canvas.get(), and this method automatically
* creates a stack frame and associates it with the method (if none has yet been associated).
*/
Canvas c = Canvas.get();
DataType datum = (DataType) model.get(address);
CellStamp<DataType> stamp = stampFactory.getStamp(address, datum);
/**
* @JTourBusStop 3, Stack-based properties for java.awt.Graphics, Changes to the clip bounds
* are exclusively narrowing:
*
* <p>Bounds changes in the Graphics object are absolute, allowing a delegated paint() method
* to expand the bounds. This is almost never necessary, and when it occurs, most often it is
* by arithmetic error in the client code. Pushing a bounds change to the Canvas exclusively
* narrows the clip, so each paint() method need only concern itself with the clip bounds that
* are logically meaningful within its context. If any paintable areas were clipped off by a
* previous method on the call stack, those areas will remain clipped off no matter what the
* current method requests. Here, the clip is set to the scrollable region of the scroll pane,
* guaranteeing that no component will accidentally paint on the scroll bars and beyond.
*
* <p>each bounds frame represents something meaningful about the visual construct; here the
* visible area of the scroll pane
*/
c.pushBounds(viewport.getCellPainter().staticContent.getScrollableBounds());
/**
* @JTourBusStop 4, Stack-based properties for java.awt.Graphics, Changes to the clip bounds
* occur in logical units to avoid messy arithmetic::
*
* <p>The process of cumulative narrowing for clip bounds lends itself naturally to simple
* arithmetic, because each set of logical bounds changes can simply be pushed in sequence. In
* this sequence of translation and narrowing, the y position is relevant to the cell bounds,
* but the x position is not. This requires the y position to be pushed before narrowing and
* the x position after, which is easy to do and easy to read in these stack-based semantics.
*/
c.pushBoundsPosition(0, -viewport.getComponent().yViewport());
c.pushBounds(
ListModelPainter.CELL_TEXT_INSET,
yTop,
viewport.getBounds().width,
stamp.getSpan(Axis.V, datum));
c.pushBoundsPosition(-viewport.getComponent().xViewport(), 0);
c.pushColor(Color.white);
c.g.fillRect(0, 0, viewport.getBounds().width, c.span().height);
/**
* @JTourBusStop 5, Stack-based properties for java.awt.Graphics, Delegate painting to the
* list cell stamp with no risk of context corruption:
*
* <p>At this point the clip bounds have been set correctly for the cell to be repainted. The
* cell stamp is now free to paint the cell according to its best understanding, knowing that
* it cannot accidentally paint outside the scrollable area, and that all its Graphics
* property change will be popped off the stack on method return.
*/
stamp.paint(c, address, datum);
}