AtlasTextView

A virtualized text view for very large text such as logs and files, with selection, copy, line numbers and follow mode.

Since 1.5.0

A text view that only lays out the lines in view, so a file of hundreds of megabytes scrolls as smoothly as a short one. The text lives in a piece tree, not in a QString. It is read-only in this release: the editing members do nothing yet.

Load a big file with beginLoad(), appendBytes() and endLoad(): the view stays responsive, loadProgress reports how far it is, and loadFailed is set if the load could not finish. The view has no file API: the caller opens the file and owns the path, symlink, size and permission checks, then feeds the bytes in. text and appendText() are for small and live content. With follow on, the view stays at the end while text is appended, until the user scrolls up; maximumLines drops the oldest lines of a log.

Only the lines in view are highlighted. syntax and syntaxTheme are stored but the built-in highlighter is not in this release; a C++ highlighter or setDecorationPairs() colours the text.

Example

AtlasTextView {
    anchors.fill: parent
    follow: true
    maximumLines: 100000
    showLineNumbers: true
}

Properties

Name	Type	Default	Description
`text`	`string`	`""`	The whole text. Setting it replaces the content at once; reading it copies everything, so avoid it for huge text; it is empty when there is not enough memory for the copy.
`readOnly`	`bool`	`true`	Reserved for editing; the view is read-only in this release.
`wrap`	`bool`	`false`	Wraps lines at the view's width. Very long lines are laid out in windows.
`font`	`font`	monospace	The font.
`tabWidth`	`int`	`4`	Width of a tab in characters.
`lineCount`	`int`	`1`	Number of lines. Read-only.
`length`	`int`	`0`	Length in UTF-16 units. Read-only.
`cursorPosition`	`int`	`0`	The caret's position.
`selectionStart`	`int`	`0`	Start of the selection. Read-only.
`selectionEnd`	`int`	`0`	End of the selection. Read-only.
`hasSelection`	`bool`	`false`	Part of the text is selected. Read-only. Use it instead of reading `selectedText` to find out.
`selectedText`	`string`	`""`	The selected text. Read-only. It is empty when the selection is larger than 32 million characters; `copy()` has the same limit.
`contentX`	`real`	`0`	Horizontal scroll offset.
`contentY`	`real`	`0`	Vertical scroll offset.
`contentWidth`	`real`		Width of the text. Read-only.
`contentHeight`	`real`		Height of the text. Read-only.
`firstVisibleLine`	`int`	`0`	First line in view. Read-only.
`lastVisibleLine`	`int`	`0`	Last line in view. Read-only.
`lineEnding`	`enum`	`LF`	The line ending found: `LF`, `CRLF`, `CR` or `Mixed`. Read-only.
`modified`	`bool`	`false`	The text changed since `markSaved()`. Read-only.
`canUndo`	`bool`	`false`	Reserved for editing. Read-only.
`canRedo`	`bool`	`false`	Reserved for editing. Read-only.
`undoLimit`	`int`	`1000`	Reserved for editing.
`loading`	`bool`	`false`	A load is running. Read-only.
`loadProgress`	`real`	`1`	Fraction loaded, 0 to 1. It is 1 when no load is running. Read-only.
`hadInvalidText`	`bool`	`false`	The loaded bytes held invalid UTF-8 that was replaced with U+FFFD. Read-only.
`loadFailed`	`bool`	`false`	The last load failed. The view keeps the clean text that arrived before the failure. Read-only.
`syntax`	`string`	`""`	Syntax name. Stored only; no built-in highlighter yet.
`syntaxTheme`	`string`	`""`	Highlighting theme name. Stored only.
`highlightLimit`	`int`	`52428800`	Longest line, in characters, that is highlighted (50 MiB).
`showLineNumbers`	`bool`	`false`	Shows the line-number gutter.
`highlightCurrentLine`	`bool`	`false`	Tints the caret's line.
`follow`	`bool`	`false`	Keeps the view at the end while text is appended. Scrolling up pauses it; scrolling to the end resumes it.
`maximumLines`	`int`	`0`	Drops the oldest lines beyond this count, also after a load or `text` is set. `0` is no limit.
`textColor`	`color`	theme text	The text colour.
`selectionColor`	`color`	theme accent	The selection colour.
`lineNumberColor`	`color`	theme muted	The gutter's number colour.

Enumerations

The values of lineEnding:

Name	Description
`LF`	Lines end with `\n`.
`CRLF`	Lines end with `\r\n`.
`CR`	Lines end with `\r`.
`Mixed`	More than one kind.

Methods

Name	Description
`textInRange(start, end)`	The text between two positions.
`positionAt(point)`	The position nearest a point in the item.
`rectangleAt(position)`	The caret rectangle at a position, in item coordinates.
`positionOfLine(line)`	The position where a line starts.
`lineOf(position)`	The line a position is on.
`columnOf(position)`	The column of a position in its line.
`beginLoad()`	Starts a streamed load and clears the text and every decoration layer.
`appendBytes(utf8)`	Adds UTF-8 bytes to a streamed load.
`endLoad()`	Finishes a streamed load.
`appendText(text)`	Appends text to the end.
`markSaved(revision)`	Marks a revision as saved, which clears `modified`.
`select(start, end)`	Selects a range.
`selectAll()`	Selects everything.
`copy()`	Copies the selection to the clipboard.
`ensureVisible(position)`	Scrolls to show a position.
`lineY(line)`	The y coordinate of a line in the content.
`setDecorationPairs(layer, pairs, style)`	Sets a decoration layer from a flat list `[start, end, ...]` with a style number. `beginLoad()` and `setText` clear every decoration layer.
`clearDecorations(layer)`	Removes a decoration layer.

Signals

Name	Description
`contentsChange(position, removed, added)`	The text changed.
`loaded()`	A load finished.

Note

Give the view an Accessible.name and, if it helps, an Accessible.description: they are what a screen reader announces. The view also exposes its text, caret and selection. It has no accessible value text, because that would be the whole file, and a screen reader gets at most about a million characters of a very long line at a time.