BlindTransitionEffectLib — Plan9Basic Documentation

Overview

BlindTransitionEffectLib reveals the target image through vertical blinds — like window blinds opening — wrapping the FireMonkey TBlindTransitionEffect component. A classic presentation-style transition.

Property	Details
Library	`BlindTransitionEffectLib`
Prefix	`blindtrans_`
Wraps	`TBlindTransitionEffect`
Functions	18
Type	Transition effect

Category	Count	Description
Creation / Destruction	2	Create and free effect
Target Image	4	Set/get/load target bitmap
Progress	2	Get/set transition progress
Number of Blinds	2	Get/set blind count
Effect Control	4	Enabled and trigger get/set
Error Handling	4	Error codes and messages

▦ Venetian Blinds: More blinds create a finer, more subtle transition. Fewer blinds (2–5) give a bold, dramatic reveal. Range is 2–100.

Cross-Platform Support

Platform	Support
Windows	✅ Full support
Linux	✅ Full support
Android	✅ Full support

Creation & Destruction

blindtrans#(parent#)

Creates a new blind transition effect attached to the specified visual control.

Parameter	Type	Description
`parent#`	Pointer	Target visual control
Returns	Pointer	Effect handle, or 0 on failure

blindtrans_free(effect#)

Destroys the effect and releases associated resources.

Error Handling

Function	Signature	Description
`blindtrans_error()`	`blindtrans_error@`	Returns last error code (0 = none)
`blindtrans_errormsg$()`	`blindtrans_errormsg$@`	Returns last error message
`blindtrans_strerror$(code)`	`blindtrans_strerror$@n`	Converts error code to text
`blindtrans_clearerror()`	`blindtrans_clearerror@`	Clears the error state

Target Image

Function	Signature	Description
`blindtrans_target#(effect#, bitmap#)`	`blindtrans_target#@##`	Sets target from bitmap pointer
`blindtrans_target#(effect#)`	`blindtrans_target#@#`	Gets target bitmap pointer
`blindtrans_loadtarget#(effect#, url$)`	`blindtrans_loadtarget#@#$`	Loads target from URL or file
`blindtrans_targetfromimage#(effect#, image#)`	`blindtrans_targetfromimage#@##`	Sets target from TImage control

Progress

Function	Signature	Description
`blindtrans_progress#(effect#, value)`	`blindtrans_progress#@#n`	Set progress (0.0–1.0)
`blindtrans_progress(effect#)`	`blindtrans_progress@#`	Get current progress

Number of Blinds

Function	Signature	Description
`blindtrans_numblinds#(effect#, value)`	`blindtrans_numblinds#@#n`	Set number of blinds (2–100)
`blindtrans_numblinds(effect#)`	`blindtrans_numblinds@#`	Get number of blinds

Count	Effect
`2–5`	Bold, dramatic reveal
`8–15`	Classic presentation-style
`20–50`	Fine, subtle transition
`50–100`	Very fine — approaches dissolve

Effect Control

Function	Signature	Description
`blindtrans_enabled#(effect#, value)`	`blindtrans_enabled#@#n`	Enable (1) or disable (0)
`blindtrans_enabled(effect#)`	`blindtrans_enabled@#`	Gets enabled state
`blindtrans_trigger#(effect#, trigger$)`	`blindtrans_trigger#@#$`	Sets trigger string
`blindtrans_trigger$(effect#)`	`blindtrans_trigger$@#`	Gets trigger string

Complete Examples

Example 1: Adjustable Blinds and Progress

╯ blinds-control.bas─◻✕
let frm# = Pointer#(0)
let img# = Pointer#(0)
let trans# = Pointer#(0)
let trkBlinds# = Pointer#(0)
let trkProg# = Pointer#(0)
let lblBlinds# = Pointer#(0)
let lblProg# = Pointer#(0)

frm# = form#("Blinds Control", 450, 450)

img# = image#(frm#)
image_bounds#(img#, 125, 20, 200, 150)
image_load#(img#, "https://picsum.photos/200/150?random=1")

trans# = blindtrans#(img#)
blindtrans_loadtarget#(trans#, "https://picsum.photos/200/150?random=2")
blindtrans_numblinds#(trans#, 5)

lblBlinds# = label#(frm#, "Blinds: 5", 50, 190)
trkBlinds# = trackbar#(frm#)
trackbar_bounds#(trkBlinds#, 50, 220, 350, 30)
trackbar_max#(trkBlinds#, 98)
trackbar_value#(trkBlinds#, 3)
trackbar_onchange#(trkBlinds#, "OnBlinds")

lblProg# = label#(frm#, "Progress: 0.00", 50, 270)
trkProg# = trackbar#(frm#)
trackbar_bounds#(trkProg#, 50, 300, 350, 30)
trackbar_max#(trkProg#, 100)
trackbar_value#(trkProg#, 0)
trackbar_onchange#(trkProg#, "OnProgress")

form_show(frm#)

function OnBlinds(sender#) local b
  let b = trackbar_value(trkBlinds#) + 2
  blindtrans_numblinds#(trans#, b)
  label_text#(lblBlinds#, "Blinds: " + str$(b))
endfunction

function OnProgress(sender#) local p
  let p = trackbar_value(trkProg#) / 100
  blindtrans_progress#(trans#, p)
  label_text#(lblProg#, "Progress: " + stri$(p, 2))
endfunction

Example 2: Animated Blinds Transition

╯ blinds-anim.bas─◻✕
let frm# = Pointer#(0)
let img# = Pointer#(0)
let trans# = Pointer#(0)
let tmr# = Pointer#(0)
let btn# = Pointer#(0)
let progress = 0
let direction = 1

frm# = form#("Animated Blinds", 400, 350)

img# = image#(frm#)
image_bounds#(img#, 100, 30, 200, 150)
image_load#(img#, "https://picsum.photos/200/150?random=1")

trans# = blindtrans#(img#)
blindtrans_loadtarget#(trans#, "https://picsum.photos/200/150?random=2")
blindtrans_numblinds#(trans#, 10)

tmr# = timer#()
timer_interval#(tmr#, 30)
timer_enabled#(tmr#, 0)
timer_ontimer#(tmr#, "Animate")

btn# = button#(frm#, "Start Transition")
button_bounds#(btn#, 130, 210, 140, 30)
button_onclick#(btn#, "StartAnim")

form_show(frm#)

function StartAnim(sender#)
  timer_enabled#(tmr#, 1)
  button_enabled#(btn#, 0)
endfunction

function Animate(sender#)
  progress = progress + (direction * 0.02)
  blindtrans_progress#(trans#, progress)
  
  if progress >= 1 then
    direction = -1
  endif
  if progress <= 0 then
    direction = 1
    timer_enabled#(tmr#, 0)
    button_enabled#(btn#, 1)
  endif
endfunction

Quick Reference

Function	Signature	Description
CREATION & DESTRUCTION
`blindtrans#(parent#)`	`blindtrans#@#`	Create effect
`blindtrans_free(effect#)`	`blindtrans_free@#`	Destroy effect
TARGET IMAGE
`blindtrans_target#(effect#, bitmap#)`	`blindtrans_target#@##`	Set target bitmap
`blindtrans_target#(effect#)`	`blindtrans_target#@#`	Get target bitmap
`blindtrans_loadtarget#(effect#, url$)`	`blindtrans_loadtarget#@#$`	Load target
`blindtrans_targetfromimage#(effect#, image#)`	`blindtrans_targetfromimage#@##`	Target from image
PROGRESS
`blindtrans_progress#(effect#, value)`	`blindtrans_progress#@#n`	Set progress (0–1)
`blindtrans_progress(effect#)`	`blindtrans_progress@#`	Get progress
NUMBER OF BLINDS
`blindtrans_numblinds#(effect#, value)`	`blindtrans_numblinds#@#n`	Set blind count (2–100)
`blindtrans_numblinds(effect#)`	`blindtrans_numblinds@#`	Get blind count
EFFECT CONTROL
`blindtrans_enabled#(effect#, value)`	`blindtrans_enabled#@#n`	Enable/disable
`blindtrans_enabled(effect#)`	`blindtrans_enabled@#`	Get enabled state
`blindtrans_trigger#(effect#, trigger$)`	`blindtrans_trigger#@#$`	Set trigger
`blindtrans_trigger$(effect#)`	`blindtrans_trigger$@#`	Get trigger
ERROR HANDLING
`blindtrans_error()`	`blindtrans_error@`	Last error code
`blindtrans_errormsg$()`	`blindtrans_errormsg$@`	Last error message
`blindtrans_strerror$(code)`	`blindtrans_strerror$@n`	Code to text
`blindtrans_clearerror()`	`blindtrans_clearerror@`	Clear error state

Library	Description
`SlideTransitionEffectLib`	Slide transition
`FadeTransitionEffectLib`	Fade transition
`DissolveTransitionEffectLib`	Dissolve transition