mirror of
https://github.com/flutter/flutter.git
synced 2026-02-20 02:29:02 +08:00
122 lines
3.7 KiB
Dart
122 lines
3.7 KiB
Dart
// Copyright 2015 The Chromium Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style license that can be
|
|
// found in the LICENSE file.
|
|
|
|
import 'package:flutter/painting.dart';
|
|
|
|
import 'box.dart';
|
|
import 'object.dart';
|
|
|
|
export 'package:flutter/painting.dart' show
|
|
FontStyle,
|
|
FontWeight,
|
|
PlainTextSpan,
|
|
StyledTextSpan,
|
|
TextAlign,
|
|
TextBaseline,
|
|
TextDecoration,
|
|
TextDecorationStyle,
|
|
TextSpan,
|
|
TextStyle;
|
|
|
|
/// A render object that displays a paragraph of text
|
|
class RenderParagraph extends RenderBox {
|
|
|
|
RenderParagraph(
|
|
TextSpan text
|
|
) : textPainter = new TextPainter(text) {
|
|
assert(text != null);
|
|
}
|
|
|
|
final TextPainter textPainter;
|
|
|
|
BoxConstraints _constraintsForCurrentLayout; // when null, we don't have a current layout
|
|
|
|
/// The text to display
|
|
TextSpan get text => textPainter.text;
|
|
void set text(TextSpan value) {
|
|
if (textPainter.text == value)
|
|
return;
|
|
textPainter.text = value;
|
|
_constraintsForCurrentLayout = null;
|
|
markNeedsLayout();
|
|
}
|
|
|
|
void layoutText(BoxConstraints constraints) {
|
|
assert(constraints != null);
|
|
assert(constraints.isNormalized);
|
|
if (_constraintsForCurrentLayout == constraints)
|
|
return; // already cached this layout
|
|
textPainter.maxWidth = constraints.maxWidth;
|
|
textPainter.minWidth = constraints.minWidth;
|
|
textPainter.minHeight = constraints.minHeight;
|
|
textPainter.maxHeight = constraints.maxHeight;
|
|
textPainter.layout();
|
|
// By default, we shrinkwrap to the intrinsic width.
|
|
double width = constraints.constrainWidth(textPainter.maxIntrinsicWidth);
|
|
textPainter.minWidth = width;
|
|
textPainter.maxWidth = width;
|
|
textPainter.layout();
|
|
_constraintsForCurrentLayout = constraints;
|
|
}
|
|
|
|
double getMinIntrinsicWidth(BoxConstraints constraints) {
|
|
layoutText(constraints);
|
|
return constraints.constrainWidth(textPainter.minIntrinsicWidth);
|
|
}
|
|
|
|
double getMaxIntrinsicWidth(BoxConstraints constraints) {
|
|
layoutText(constraints);
|
|
return constraints.constrainWidth(textPainter.maxIntrinsicWidth);
|
|
}
|
|
|
|
double _getIntrinsicHeight(BoxConstraints constraints) {
|
|
layoutText(constraints);
|
|
return constraints.constrainHeight(textPainter.size.height);
|
|
}
|
|
|
|
double getMinIntrinsicHeight(BoxConstraints constraints) {
|
|
assert(constraints.isNormalized);
|
|
return _getIntrinsicHeight(constraints);
|
|
}
|
|
|
|
double getMaxIntrinsicHeight(BoxConstraints constraints) {
|
|
assert(constraints.isNormalized);
|
|
return _getIntrinsicHeight(constraints);
|
|
}
|
|
|
|
double computeDistanceToActualBaseline(TextBaseline baseline) {
|
|
assert(!needsLayout);
|
|
layoutText(constraints);
|
|
return textPainter.computeDistanceToActualBaseline(baseline);
|
|
}
|
|
|
|
bool hitTestSelf(Point position) => true;
|
|
|
|
void performLayout() {
|
|
layoutText(constraints);
|
|
size = constraints.constrain(textPainter.size);
|
|
}
|
|
|
|
void paint(PaintingContext context, Offset offset) {
|
|
// Ideally we could compute the min/max intrinsic width/height with a
|
|
// non-destructive operation. However, currently, computing these values
|
|
// will destroy state inside the painter. If that happens, we need to
|
|
// get back the correct state by calling _layout again.
|
|
//
|
|
// TODO(abarth): Make computing the min/max intrinsic width/height
|
|
// a non-destructive operation.
|
|
layoutText(constraints);
|
|
textPainter.paint(context.canvas, offset);
|
|
}
|
|
|
|
// we should probably expose a way to do precise (inter-glpyh) hit testing
|
|
|
|
String debugDescribeChildren(String prefix) {
|
|
return '$prefix \u2558\u2550\u2566\u2550\u2550 text \u2550\u2550\u2550\n'
|
|
'${text.toString("$prefix \u2551 ")}\n'
|
|
'$prefix \u255A\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n'
|
|
'$prefix\n';
|
|
}
|
|
}
|