Floating window in Emacs

Now you can create a floating window in Emacs. For a quick demo, create vertical split windows (C-x 3). Then with point in right hand window, execute following command in mini-buffer.

(progn (setq w (selected-window)) (window-make-popup w 107 287))

 

Why prefer window over frame?

An Emacs frame is created using X top level window. Hence Emacs frames don't share X11 resources. However, multiple Emacs windows are part of the same top-level window and hence share X11 resources allocated for the X top level window.

Code:

https://gitlab.com/atamariya/emacs/-/blob/dev/src/window.c
https://gitlab.com/atamariya/emacs/-/blob/dev/src/window.h
https://gitlab.com/atamariya/emacs/-/blob/dev/src/xdisp.c

Lessons Learnt

  • Emacs uses display optimization to reduce the amount of area that need to be repainted. redisplay() is the entry point for this logic (xdisp.c and dispnew.c). In most cases, it's only updating the position of point in the current line.
  • Frame based display is used for terminals and window based display is used for GUI.
  • Emacs display on X is primarily one outer frame, one edit region and multiple scrollbars. Outer frame is top level X window and others are child windows. Scroll bars, being windows, will always be drawn on TOP of the edit region.
  • C-l allows you to position your current line at the top, center or bottom of the screen.
  • Use calln to call Lisp functions in C.eg. call1 is used to call a Lisp function with one argument.
  • In the code, stretch glyph refers to glyph for TAB and highlighted glyph at line end.
  • If for root window, new_pixel != pixel_width, it's child can't be deleted. So ensure these values match before deleting.
  • window_resize_check() and window_resize_apply() should always be called in order.
  • window--dump-window() and window--dump-frame() functions can be useful for obtaining some important metrics.
  • Structure of an Emacs window .

 


Comments

Post a Comment

Popular posts from this blog

GNU Emacs as a Comic Book Reader

Image
  Comics are available in digital format as a collection of images in a compressed ZIP or RAR file (.cbz or .cbr file extension respectively). These can be enjoyed in GNU Emacs with full access to image viewing capabilities using keybindings.   # Make sure you have unrar installed for CBR files # apt install unrar   (require 'arc2-mode)   (setq archive-summarize-files-fn 'archive-summarize-files-as-thumb)     Note: The archive-mode is capable of displaying the list of files in an archive; though it depends on external tools for extraction. For JPG and PNG, Emacs can resize the image without external convertor (ie. imagemagick). However, some menu options for image transformations in image-mode might not be available. Use the following patch for image-mode.el . @@ -460,16 +460,16 @@ image-mode-map       :help "Show image as hex"]      "--"      ["Fit to Window Height" image-transform-fit-to-height -     :visible (eq image-type 'imagemagick) +
Read more

Data Visualization with GNU Emacs

Image
    GNU Emacs can be used for quick data visualization in combination with Gnuplot. When you have some data and you want to visualize what the correlation looks like, this command comes in handy. No need for any setup - no data file and no Gnuplot script. The command below uses some sensible defaults for trivial cases. If the first line contains string label, the same is used as a key label for the value and/or axes' names as appropriate. If there's a single column of data, it is used as Y value. If there's more than one column, first column is used as X value and other columns are plotted along Y-axis. Takes care of comma or whitespace separator. Note: The latest version of the code is available at the end of the post. Options available in latest version   - Install gnuplot executable and gnuplot Elisp package . - Evaluate the defun ( C-M-x ). - Select a data range using rectangle command copy-rectangle-as-kill (C-x r M-w). - Run M-x  gnuplot-rectangle. This opens the g
Read more

Tinylisp and Multi-threaded Emacs

Image
TAME-ing the beast!! Here's a fork of tinylisp and a glimpse of a possible multi-threaded future. Below is the content of the file a.el in the demo. It creates one read thread which waits for non-nil value of global-var and a set thread which sleeps for 5s before modifying global-var and notifying the waiting threads. Since these are running in separate threads, main loop is free for user input. (define list (lambda args args)) (define defun (macro (f v . x) (list 'define f (list 'lambda v (cons 'progn x))))) (setq make-condition-variable make-cond) (setq condition-wait cond-wait) (setq condition-notify cond-signal) (setq message p) (setq sleep-for sleep) (setq global-var nil) ;; Create a mutex and an associated condition variable (setq mutex (make-mutex "mutex")) (setq cond-var (make-condition-variable mutex "cond-var")) ;; Read and set functions used by read and set threads (defun set-global-var ()   (mutex-lock mutex)   (sleep 5)   (setq global-
Read more