Dr Racket get pixmap width/height - racket

I'm working on a project for university and was wondering if it is possible to get the height and width of a pixmap in some way. I know it is possible for rectangles and circles and stuff...
I'm using this to draw the pixmap, file is a jpg:
(define (draw-image! x y file)
(let ((posn (my-make-posn x y)))
((draw-pixmap MainWindow) file posn)))

Perhaps you already know this, but the library you're using is deprecated: in the manual, you'll see that it's part of the "Legacy Library."
Here's a simple program that loads a picture from a jpg, displays it, and prints its dimensions, using the 2htdp/image library:
#lang racket
(require 2htdp/image)
(define pic
(bitmap "/Users/clements/Pictures/Photo Booth Library/Pictures/Photo on 2012-02-12 at 10.53.jpg"))
pic
(image-height pic)
(image-width pic)
You'll probably have to update the path....

Related

What is the error in the following racket code?

;creating traffic signal image
(require 2htdp/image)
(define (bulb c)
(circle 10 "solid" c))
(above (bulb "red")
(bulb "yellow")
(bulb "green"))
The Error Displayed is:. Module Language: there can only be one expression in the definitions window in: (define (bulb c) (circle 10 "solid" c))
Interactions disabled.
///I can't figure out the error
DrRacket is failing to recognize the language being used in your code. You need to choose a language manually. It looks like you are following the first chapters of the HtDP textbook, so I recommend going for the Beginning Student Language. You can do so by:
adding #lang htdp/bsl at the beginning of your file
using the picker at the bottom of the DrRacket window:

How to make inline images responsive in org-mode?

When I toggle inline image using org-toggle-inline-images which shows the image(s). However, when the image it too large it will overflow the editor's frame (See screenshot below).
How to make the image responsive which means the max size of the image should never exceed the width of window size.
Of course, I can use the code below to fix the size of the image. But what I truly want is some kind of responsive image displaying.
(setq org-mode-actual-width 600)
Thanks for your time viewing this question.
From the documentation of org-image-actual-width:
Documentation:
Should we use the actual width of images when inlining them?
When set to t, always use the image width.
When set to a number, use imagemagick (when available) to set
the image's width to this value.
When set to a number in a list, try to get the width from any
#+ATTR.* keyword if it matches a width specification like
#+ATTR_HTML: :width 300px
and fall back on that number if none is found.
When set to nil, try to get the width from an #+ATTR.* keyword
and fall back on the original width if none is found.
So you could use the attribute #+ATTR_HTML to specify the width. It has to be specified manually though. Is this responsive enough?
The function below re-renders the org-mode inline images whenever the window is resized by using hooks. It shrinks the image only when the window is displaying less than 80 columns (usually 1/3 of the screen). I believe it works better than always rendering in window width.
(defun org-image-resize (frame)
(when (derived-mode-p 'org-mode)
(if (< (window-total-width) 80)
(setq org-image-actual-width (window-pixel-width))
(setq org-image-actual-width (* 80 (window-font-width))))
(org-redisplay-inline-images)))
(add-hook 'window-size-change-functions 'org-image-resize)
GIF Demo of the code above
If you want the image just matching the size of your window width:
(defun org-image-resize (frame)
(when (derived-mode-p 'org-mode)
(setq org-image-actual-width (window-pixel-width))
(org-redisplay-inline-images)))
(add-hook 'window-size-change-functions 'org-image-resize)
Or change the (window-pixel-width) into (- (window-pixel-width) 20) if you want some margin on the right side.

Setting Both `fullheight` and `width` in Emacs on OS X

I find the default size of the Emacs frame a little too small. From reading around I know that I can set the height and width quite easily with something like the following:
;;; 140 x 60 window size
(setq default-frame-alist '((width . 140) (height . 60)))
Which works great on my external monitor, however it is a litte too big for the laptop display. I can solve the height problem by changing to the follwing:
;;; automatically set the height
(setq default-frame-alist '((fullscreen . fullheight)))
Which sets the frame to be as tall as possible for the current screen. I can't however set the width of the frame if I use this method. Adding (width . 140) to the above alist sets the width to the right value but also sets the height to the default height again.
When I see the frame appear it sets itself to the full height, and then sets the width to the value I requested, and shrinks in height.
I can overcome this problem with the following code:
;;; Full height for the default window
(setq default-frame-alist
'((fullscreen . fullheight)))
;; Set the width in a hook and have all windows inherit
(setq frame-inherited-parameters
'(width height))
(add-hook 'after-init-hook
(lambda ()
(set-frame-parameter nil 'width 140)))
Which uses a hook to set the width of the first frame to the value I want, and then sets all other windows to inherit this value.
This isn't very elegant however, so the question is "how can I accomplish this in a simpler (or less hackish) way?".
If you want to see my exact init.el script, take a look at this gist
TL;DR
How can I set both the width of a frame, and set the frame to be as tall as possible on the current monitor, on OS X? It seems you can't specify (width . 140) and (fullscreen . fullheight) in the default-frame-alist.
I have come up with a solution to this. I explicitly calculate the height of the window rather than relying on (fullscreen . fullheight) to do it for me.
The updated code to set the values for the height and width is quite simple:
;;; Nice size for the default window
(defun get-default-height ()
(/ (- (display-pixel-height) 120)
(frame-char-height)))
(add-to-list 'default-frame-alist '(width . 140))
(add-to-list 'default-frame-alist (cons 'height (get-default-height)))
In this code the subtraction of 120 from the height of the screen makes sure that the height of the window takes into account the height of the dock and the menubar. For correct results you will have to make sure that this code is executed after you have chosen the font face to use, otherwise the computed height value will not be valid.
Placing the height calculation in its own function should allow special casing certain operating systems and versions. This method also has the added advantage that is faster to open the window as it doesn't "animate" the height to the full height value.
The last paragraph of the help text for display-pixel-height is:
For graphical terminals, note that on "multi-monitor" setups this
refers to the pixel height for all physical monitors associated
with DISPLAY. To get information for each physical monitor, use
‘display-monitor-attributes-list’.
What got me to this page is what looks like a bug in the X11 implementation but I'm not sure yet. In any case, display-pixel-height works only often but not always.
Sample output from display-monitor-attributes-list is:
(
(
(geometry 0 0 1920 1080)
(workarea 0 25 1920 1055)
(mm-size 478 268)
(frames #<frame *scratch* 0x14489a030>)
(source . "NS")
)
(
(geometry 192 1080 1512 982)
(workarea 192 1080 1512 950)
(mm-size 301 195)
(frames)
(source . "NS")
)
)
In my case, I have a laptop (bottom entry) and a monitor connected to it (the top entry).
One possible solution would be to go through the list, find the monitor with the largest height and do the computations based upon that height and then at the end also do something like (set-frame-position nil 192 1080) where the two coordinates come from the top and left coordinates (the first two values of geometry and work area of the monitor that has the greatest height.
It appears that the workarea is the more prudent set of values to use.
And to further make a robust solution, a hook should be added to window-configuration-change-hook so that when a monitor is added or removed, things will get updated.
I am currently asking some questions on the Emacs developers mailing list and working on a solution for myself. I plan to return and update this entry when I have a solution that I'm happy with but thought this information may be of use to others as is.
Update:
There is no bug. x-display-pixel-height has various X11 rude facts of life. For more details, see this reply.
The "Frame Layout" node in the info documentation for ELisp as a description of the Inner and Outer Frame along with many other concepts that are pertinent to this question.
Here is my current solution. I have not done the hook yet. I don't claim to know how to program in lisp but this code is working for me.
(defun workarea-height ( monitor )
"MONITOR is an entry from `display-monitor-attributes-list' The
height entry (4th value) of the 'workarea' is returned"
(nth 4 (assoc 'workarea monitor)))
(defun monitor-with-largest-height-helper ( a b )
"Compares the height of the workarea of two monitor entries such as
those contained in the output of `display-monitor-attributes-list'"
(let* ((a-height (workarea-height a))
(b-height (workarea-height b)))
(if (> a-height b-height)
a
b)))
(defun monitor-with-largest-height ()
"Returns the monitor entry from `display-monitor-attributes-list'
with the largest 'workarea' height"
(cl-reduce #'monitor-with-largest-height-helper
(display-monitor-attributes-list)))
(defun largest-monitor-height ()
"Returns the usable height in lines of the largest monitor currently
attached"
(let* ((largest-monitor (monitor-with-largest-height)))
(/ (- (workarea-height largest-monitor)
(- (frame-outer-height)
(frame-inner-height)))
(frame-char-height))))
(defun my-resize-frame-height ()
"Resizes the current frame to the full height of the largest monitor
currently attached."
(interactive)
(set-frame-height nil (largest-monitor-height)))
The other work left to do is to make sure the left and top of the frame are within the area of the largest monitor to the frame will be displayed on that monitor.

How to recenter an Emacs buffer around an overlay

I want to recenter an Emacs buffer so as to show as much as possible of an overlay and of its context around it. Specifically, I want this behavior:
If the overlay fits in the visible window, I want to show as much as line before it as lines after it;
Otherwise, I want the beginning of the overlay to be shown.
This behavior is somewhat similar to what I see when using different regions highlighted in ediff.
Is there a not-so-complicated way to achieve this? I tried to look into the ediff code (specifically ediff-util.el) but things seems very complicated to me.
I'm not quite sure what usage you're looking for, but this code should do what you want.
It can be called with an overlay, or if called interactively, will choose one of the overlays at the current position and do the action on it.
(defun make-overlay-visible (overlay)
"given an overlay, center it on the window
(or make beginning visible if it cannot fit in the window)"
(interactive (list (car (overlays-at (point)))))
(when overlay
(goto-char (overlay-start overlay))
(recenter 0)
(when (and (pos-visible-in-window-p (overlay-start overlay))
(pos-visible-in-window-p (overlay-end overlay)))
(goto-char (/ (+ (overlay-start overlay) (overlay-end overlay)) 2))
(recenter))))

How to resize a buffer so it only takes a small part of the screen?

In Emacs how can I resize a buffer so it only takes a small part of the screen ?
Is there any way ?
I would like to have the src taking 70% of the screen and a file manager in the other 30%
Set width of current window on current frame to ~ 70%:
(window-resize nil (- (truncate (* 0.7 (frame-width))) (window-width)) t)
The other windows are shrunk automatically. If you want to adjust more than one it gets more difficult.
As command:
(defun window-resize-to-70-percent ()
(interactive)
(window-resize nil (- (truncate (* 0.7 (frame-width))) (window-width)) t))
Use separate window-manager frames for individual buffers (by default). Automatically shrink-fit the frames to fit the buffer content.
See One-On-One Emacs, in particular, libraries fit-frame.el and autofit-frame.el.