Plan DPI and text-layout tests — Boundary detective

PART I

Warm-up

Reconnect with a useful idea before starting plan dpi and text-layout tests. In one or two sentences, describe the input, output or host boundary from the previous exercise that this lesson builds on. If you are arriving directly, skim the worked example first; there is no locked prerequisite.

A rough note is enough. You can revise it after the example.

PART II

Instruction & guided example

Define fractional-pixel rounding explicitly

DPI and text layout need explicit unit and measurement contracts. A logical layout size differs from physical pixels, and glyph measurements differ across fonts, scales and languages. Use small numeric budgets for predictions and native observations for actual rendering; no WUIX engine runs on this school site.

A boundary is at10.2 logical units and width5.2 at scale1.25. Host contract rounds the left edge down and right edge up to cover the full logical interval.

Worked reasoning: Logical right edge15.4 scales to19.25; left scales to12.75. Rounded edges are12 and20, so physical coverage is8 pixels. Rounding width6.5 independently to7 can disagree with edge coverage.

Failed alternative: Guessing one universal nearest-pixel rule contradicts the supplied outward-edge policy.

Worked reasoning and supplied artifact

Left10.2*1.25=12.75 ->floor12
Right15.4*1.25=19.25 ->ceil20
Covered width20-12=8 physical px
Independent width rounding is not this contract

Illustrative example from the proposed WillowScript design. The language and WUIX/WMATH/WDB/WAUDIO/WTMP services are not implemented in the supplied source. This site has no interpreter, VM or native host and does not execute or certify the snippet.

Try the guided change

Reconstruct the supplied worked case first: list its inputs, intermediate decisions and final artifact. Compare each row with the explanation and identify exactly where the rejected alternative fails. Then use the changed inputs in Part IV for independent work.

• Write the supplied inputs and initial state before following the example.
• Reconstruct each intermediate calculation or host decision, then compare with the worked artifact.
• Explain why the contrasting alternative fails before attempting the changed inputs in Part IV.

PART III

Take a breather

Step back after the guided example. Look away from the screen, stretch, or reread your prediction. This is an optional learning pause, not a timer or an assessment gate.

When you return, try to name the lesson’s key idea without copying its wording. If that feels difficult, return to Part II and trace one line rather than restarting the entire lesson.

PART IV

Independent practice

Project context: Accessible service console. Build a small, understandable change around plan dpi and text-layout tests.

Use left3.2, width4.4, scale1.5 under outward-edge rounding. Compute both physical edges and coverage.

What to produce

An edge-based fractional rounding trace with the host rule stated.

• State the intended behavior in a sentence before editing.
• Use only source-backed syntax and the host services whose contract you have been given.
• Record a normal case and a boundary or unavailable-resource case.
• Label hand predictions separately from anything actually measured in a supplied toolchain.

Syntax colors are a reading aid, not a compiler. The line you are editing stays uncolored until you move to a different line; capitalization is never changed. Drafts stay on this browser and code is not executed.

import wuix.widget.button;
import wuix.layout;
domain Login {
    const screen = {
        layout: { type: "column", padding: [24, 32], gap: 16 },
        components: [{ type: "text", value: "Welcome back" }]
    };
    fnc show() -> void {
        wuix.mount("main", screen);
    }
}

PART V

Self-check

Use this check to notice what to revisit. It does not award a private course grade, block another page or claim to verify compiled code. Every answer has a learning explanation.

You may keep exploring even if you are unsure. Use the hint, compare the trace, and revise your explanation.

PART VI

Recap & small task

Bring the idea back to the mod feature you are building. A useful recap connects the mechanism to a decision you can make in your own code.

• Define fractional-pixel rounding explicitly
• Use left3.2, width4.4, scale1.5 under outward-edge rounding. Compute both physical edges and coverage.
• Separate source-backed behavior, host requirements and untested predictions.

One small recap task

Determine the rounding policy before treating a one-pixel difference as a defect.

This marks your personal practice record only. It is not a certification or an official workspace assessment.