Hello,
If I call stream-pointer-position on the stream without scroller, it returns an expected position. However, when the stream has a scroller, the function returns the position inside viewport regardless position of scrollbars, i. e. from upper left corner of viewport, not from the stream's origin. I have played with map-sheet-position-to-child and map-sheet-position-to-parent but faced with the different behaviour of these functions, which depends on how scrolling declared inside define-application-frame. To be more presise, it depends on internal structure of application-pane with scroller: in McCLIM it has also border-pane as a parent (why?). I think, the programmer shouldn't keep in mind such implementation details.
So, what is the right behavior of stream-pointer-position if the stream has a scroller? Shouldn't it return the real coordinates on stream as pointer events do?
Specification says:
stream-pointer-position [Generic Function]
Arguments: stream &key pointer
Summary: Returns the current position of the pointing device pointer for the extended input stream stream as two values, the x and y positions in the stream's drawing surface coordinate system. If pointer is not supplied, it defaults to the stream-primary-pointer of the stream.
"Evgeny M. Zubok" evgeny.zubok@tochka.ru writes:
So, what is the right behavior of stream-pointer-position if the stream has a scroller? Shouldn't it return the real coordinates on stream as pointer events do?
I found an answer to my question. I have just found CLIM implementation from Allegro CL (I only used it with lesstif backend instead motif).
To test I create a pane 'canvas' with :min-height 2000 :min-width 2000 and layout (scrolling (:height 500 :width 500) ...). In define-presentation-action for blank-area I call stream-pointer-position and print string "TEST", starting that point . In Allegro's CLIM implementation the strings appear where I have pressed pointer button; in McCLIM they appear only at the first page of canvas, even if I have pressed button on blank-area on other pages. So, I think, this is bug in McCLIM.
Sample code:
(defpackage :stream-pointer-position-bug (:use :clim-lisp :clim))
(in-package :stream-pointer-position-bug)
(defun run () (run-frame-top-level (make-application-frame 'main)))
(define-application-frame main () () (:menu-bar nil) (:panes (canvas (scrolling (:height 500 :width 500) (make-pane 'application-pane :display-time nil :background +black+ :foreground +white+ :min-width 2000 :min-height 2000 :scroll-bars t :display-function #'draw-circle :name 'canvas :output-record (make-instance 'standard-tree-output-history))))) (:layouts (:main canvas)))
(defun draw-circle (frame pane) (declare (ignore frame)) (draw-circle* pane 1500 1500 70 :filled t :ink +yellow+))
(define-presentation-action test (blank-area nil main :gesture :select) (presentation window) (declare (ignore presentation)) (multiple-value-bind (x y) (stream-pointer-position window) (draw-text* window "TEST" x y)))
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Evgeny M. Zubok