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core.imageview

An image view that allows zooming in and out an image.

local imageview = require "core.imageview"

__index​

(field) __index: core.object

Base class providing OOP functionality for Lua. All classes in Pragtical inherit from Object.

background​

(field) background: canvas?

Core functionality that allows rendering into a separate surface.

bg_color​

(field) bg_color: renderer.color

Array of bytes that represents a color used by the rendering functions.

bg_mode​

(field) bg_mode: "grid"|"none"|"solid"

context​

(field) context: 'application'|'session'

current_scale​

(field) current_scale: number

cursor​

(field) cursor: string

errmsg​

(field) errmsg: string?

h_scrollbar​

(field) h_scrollbar: core.scrollbar

Scrollable viewport indicator with draggable thumb. Supports both vertical and horizontal orientation with configurable alignment. Uses a "normal" coordinate system internally that treats all scrollbars as vertical-end-aligned, then transforms to the actual orientation/alignment.

height​

(field) height: number

hovered_scrollbar​

(field) hovered_scrollbar: boolean

image​

(field) image: canvas?

Core functionality that allows rendering into a separate surface.

image_scaled​

(field) image_scaled: canvas?

Core functionality that allows rendering into a separate surface.

mouse​

(field) mouse: table

mouse_pressed​

(field) mouse_pressed: boolean

path​

(field) path: string?

position​

(field) position: core.view.position

prev_size​

(field) prev_size: table

scroll​

(field) scroll: core.view.scroll

scrollable​

(field) scrollable: boolean

size​

(field) size: core.view.position

super​

(field) super: core.view

Base view.

type​

(field) type: string

v_scrollbar​

(field) v_scrollbar: core.scrollbar

Scrollable viewport indicator with draggable thumb. Supports both vertical and horizontal orientation with configurable alignment. Uses a "normal" coordinate system internally that treats all scrollbars as vertical-end-aligned, then transforms to the actual orientation/alignment.

width​

(field) width: number

zoom_mode​

(field) zoom_mode: "fit"|"fixed"

zoom_scale​

(field) zoom_scale: number

core.imageview.zoommode​

core.imageview.zoommode:
    | "fit"
    | "fixed"

from_state​

function core.imageview.from_state(state: table)
  -> core.imageview|nil

is_supported​

function core.imageview.is_supported(path: string)
  -> supported: boolean
  2. file_extension: string

Check if an image type is supported by its filename extension.

__call​

(method) core.object:__call(...any)
  -> obj: core.object

Metamethod allowing class to be called like a constructor. Enables syntax: local obj = MyClass(args) instead of MyClass:new(args) Automatically creates instance and calls new() with provided arguments.

@return obj — The new instance of the class

__tostring​

(method) core.imageview:__tostring()
  -> string

clamp_scroll_position​

(method) core.view:clamp_scroll_position()

Clamp scroll position to valid range (0 to max scrollable size). Called automatically by update(). Override get_scrollable_size() to customize.

draw​

(method) core.imageview:draw()

draw_background​

(method) core.view:draw_background(color: renderer.color)

Draw a solid background color for the entire view. Commonly called at the start of draw() methods.

draw_image​

(method) core.imageview:draw_image()

draw_scrollbar​

(method) core.view:draw_scrollbar()

Draw the view's scrollbars. Commonly called at the end of draw() methods.

extend​

(method) core.object:extend()
  -> cls: core.object

Create a new class that inherits from this one. Returns a new class with this class as its parent. Example: local MyClass = Object:extend()

@return cls — The new class table

extends​

(method) core.object:extends(T: any)
  -> extends: boolean

Check if object inherits from the given type (inheritance-aware). Use this to check class hierarchy. Example: view:extends(View) returns true for View and all subclasses

@param T — Class to check inheritance from

@return extends — True if object is T or inherits from T

get_content_bounds​

(method) core.view:get_content_bounds()
  -> x1: number
  2. y1: number
  3. x2: number
  4. y2: number

Get the content bounds in content coordinates (accounting for scroll).

@return x1 — Left edge

@return y1 — Top edge

@return x2 — Right edge

@return y2 — Bottom edge

get_content_offset​

(method) core.view:get_content_offset()
  -> x: number
  2. y: number

Get the top-left corner of content area in screen coordinates. Accounts for scroll offset. Use for drawing content at correct position.

@return x — Screen x coordinate

@return y — Screen y coordinate

get_h_scrollable_size​

(method) core.imageview:get_h_scrollable_size()
  -> number

get_module​

(method) core.view:get_module()
  -> path: string?

Returns the module path of this view.

This method resolves the Lua module name that loaded the concrete view class (for example "core.view").

If the view class cannot be associated with any loaded module, nil is returned.

get_name​

(method) core.imageview:get_name()
  -> string

get_scrollable_size​

(method) core.imageview:get_scrollable_size()
  -> number

get_state​

(method) core.imageview:get_state()
  -> table

is​

(method) core.object:is(T: any)
  -> is_exact: boolean

Check if object is exactly of the given type (no inheritance check). Use this for strict type matching. Example: view:is(DocView) returns true only if view is a DocView, not a subclass

@param T — Class to check against

@return is_exact — True if object is exactly type T

is_class_of​

(method) core.object:is_class_of(T: any)
  -> is_instance: boolean

Check if the given object is exactly an instance of this class. Inverse of is() - checks if T is an instance of self. Example: DocView:is_class_of(obj) checks if obj is exactly a DocView

@param T — Object to check

@return is_instance — True if T is exactly an instance of this class

is_extended_by​

(method) core.object:is_extended_by(T: any)
  -> is_extended: boolean

Check if the given object/class inherits from this class. Inverse of extends() - checks if T is a subclass of self. Example: View:is_extended_by(DocView) checks if DocView inherits from View

@param T — Object or class to check

@return is_extended — True if T inherits from this class

load​

(method) core.imageview:load(path?: string)
  -> loaded: boolean
  2. errmsg: string?

Loads the given image into the view.

move_towards​

(method) core.view:move_towards(t: table, k: string|number, dest: number, rate?: number, name?: string)

Smoothly animate a value towards a destination. Use this for animations instead of direct assignment.

@param t — Table containing the value

@param k — Key in table

@param dest — Target value

@param rate — Animation speed (0-1, default 0.5, higher = faster)

@param name — Transition name (for config.disabled_transitions)

new​

(method) core.imageview:new(path?: string, zoom_mode: any, zoom_scale: any)

Constructor

on_file_dropped​

(method) core.view:on_file_dropped(filename: string, x: number, y: number)
  -> consumed: boolean

Handle file drop events (drag and drop from OS). Override to handle dropped files. Return true to consume event.

@param filename — Absolute path to dropped file

@param x — Screen x where file was dropped

@param y — Screen y where file was dropped

@return consumed — True to consume event, false to propagate

on_ime_text_editing​

(method) core.view:on_ime_text_editing(text: string, start: number, length: number)

Handle IME (Input Method Editor) text composition events. Override for IME support in text editors. Called during composition.

@param text — Composition text being edited

@param start — Start position of selection within composition

@param length — Length of selection within composition

on_mouse_left​

(method) core.view:on_mouse_left()

Called when mouse leaves the view's area. Override to clear hover states. Base implementation notifies scrollbars.

on_mouse_moved​

(method) core.imageview:on_mouse_moved(x: number, y: number, dx: number, dy: number)
  -> boolean

on_mouse_pressed​

(method) core.imageview:on_mouse_pressed(button: 'left'|'right', x: number, y: number, clicks: integer)
  -> boolean

on_mouse_released​

(method) core.imageview:on_mouse_released(button: 'left'|'right', x: number, y: number)

on_mouse_wheel​

(method) core.imageview:on_mouse_wheel(d: number)
  -> boolean

on_scale_change​

(method) core.view:on_scale_change(new_scale: number, prev_scale: number)

Called when DPI scale changes (display moved, zoom changed, etc.). Override to adjust sizes, padding, or other scale-dependent values.

@param new_scale — New scale factor (e.g., 1.0, 1.5, 2.0)

@param prev_scale — Previous scale factor

on_text_input​

(method) core.view:on_text_input(text: string)

Handle text input events (typing, IME composition). Override for text editing. Called after IME composition completes.

@param text — Input text (may be multiple characters)

on_touch_moved​

(method) core.view:on_touch_moved(x: number, y: number, dx: number, dy: number, i: number)

Handle touch move events (touchscreen/trackpad gestures). Override for touch-specific behavior. Base implementation handles scrolling.

@param x — Current touch x coordinate

@param y — Current touch y coordinate

@param dx — Delta x since last position

@param dy — Delta y since last position

@param i — Touch finger/pointer index

scale_image​

(method) core.imageview:scale_image()

Scale the currently loaded image depending on the current zoom mode and scale factor.

scrollbar_dragging​

(method) core.view:scrollbar_dragging()
  -> dragging: boolean

Check if user is currently dragging either scrollbar.

@return dragging — True if scrollbar drag is in progress

scrollbar_hovering​

(method) core.view:scrollbar_hovering()
  -> hovering: boolean

Check if mouse is hovering over either scrollbar track.

@return hovering — True if mouse is over scrollbar

scrollbar_overlaps_point​

(method) core.view:scrollbar_overlaps_point(x: number, y: number)
  -> overlaps: boolean

Check if a screen point overlaps either scrollbar. Useful for determining cursor style or handling clicks.

@param x — Screen x coordinate

@param y — Screen y coordinate

@return overlaps — True if point is over vertical or horizontal scrollbar

supports_text_input​

(method) core.view:supports_text_input()
  -> boolean

Whether this view accepts text input (enables IME). Override and return true for text editors and input fields.

try_close​

(method) core.view:try_close(do_close: function)

Called when view is requested to close (e.g., tab close button). Override to show confirmation dialogs for unsaved changes. Example: core.command_view:enter("Save?", \{submit = do_close\})

@param do_close — Call this function to actually close the view

update​

(method) core.imageview:update()

update_scrollbar​

(method) core.view:update_scrollbar()

Update scrollbar positions and sizes. Called automatically by update(). Rarely needs to be called manually.

zoom_in​

(method) core.imageview:zoom_in()

Increases the image scale.

zoom_out​

(method) core.imageview:zoom_out()

Decreases the image scale.

zoom_reset​

(method) core.imageview:zoom_reset()

Sets image size to original.