harmony 鸿蒙ArkGraphics2D Changelog

2025-06-12
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ArkGraphics2D Changelog

cl.arkgraphics2d.1 Added ohos.graphics2d.text.adapter_text_height to the metadata Tag of the Main Module to Enable a New Line Height Calculation Rule Globally

Access Level

Public API

Reason for Change

To further improve text rendering, a field is introduced to enable applications to adopt a new line height calculation rule across the entire application.

Change Impact

This change is a compatible change.

The ohos.graphics2d.text.adapter_text_height field is added to the metadata tag in the module.json5 file of the main module to enable the new line height calculation rule for the application.

{
    "module": {
        "name": "test",
        "type": "entry",
        "metadata": [
            {
                "name": "ohos.graphics2d.text.adapter_text_height",
            }
        ]
    }
}

If ohos.graphics2d.text.adapter_text_height is not configured, the default line height calculation rule is used. The default rule is calculated as follows:

For a font size of fontSize (px), the rule is (|descender|+|ascender|)/unitsPerEm * fontSize.

If ohos.graphics2d.text.adapter_text_height is configured in the main module, the default line height calculation rule is enabled for the entire application. The new rule is as follows:

For custom fonts: For a font size of fontSize (px), the rule is (|yMin|+|yMax|) /unitsPerEm * fontSize.
For system fonts: For a font size of fontSize (px), the rule is (|yMin|+|yMax|) /unitsPerEm * fontSize. For system fonts, the line height calculation is based on the HarmonyOS_Sans.ttf file.

You can use the font inspector to view the parameters in a font file and learn about the line height and effect of the font.

The following uses the HarmonyOS_Sans.ttf file as an example to describe the default and new rules for calculating the line height.

Parameters in the HarmonyOS_Sans.ttf font file

The figure shows that at a 1000 px font size for HarmonyOS_Sans, yMin is -271, yMax is 1056, ascender is 928, and descender is -244. 1. According to the default rule, the line height for 50 px HaromonyOS_Sans is (|-244|+|928|)/1000 * 50 = 58.6 px. 2. According to the new rule, the line height for 50 px HaromonyOS_Sans is (|-271|+|1056|)/1000 * 50 = 66.35 px.

Start API Level

Change Since

OpenHarmony SDK 5.0.0.46

Key API/Component Changes

N/A

Adaptation Guide

The new line height calculation rule will be used as the default rule in later versions. For compatibility and UI display, you are advised to use this rule during application development.

After the setting of ohos.graphics2d.text.adapter_text_height in the main module, the application UI might display unexpected issues like text being cut off, elements overlapping, or shifts in the relative positioning of content. You need to adjust the layouts of the affected pages.