Struct druid::Scale

pub struct Scale { /* fields omitted */ }

Coordinate scaling between pixels and display points.

This holds the platform DPI and the equivalent scale factors.

Pixels and Display Points

A pixel (px) represents the smallest controllable area of color on the platform. A display point (dp) is a resolution independent logical unit. When developing your application you should primarily be thinking in display points. These display points will be automatically converted into pixels under the hood. One pixel is equal to one display point when the platform scale factor is 1.0.

Read more about pixels and display points in the druid book.

Converting with Scale

To translate coordinates between pixels and display points you should use one of the helper conversion methods of Scale or for manual conversion scale_x / scale_y.

Scale is designed for responsive applications, including responding to platform DPI changes. The platform DPI can change quickly, e.g. when moving a window from one monitor to another.

A copy of Scale will be stale as soon as the platform DPI changes.

Implementations

impl Scale

pub fn from_dpi(dpi_x: f64, dpi_y: f64) -> Scale

Create a new Scale state based on the specified DPIs.

Use this constructor if the platform provided DPI is the most accurate number.

pub fn from_scale(scale_x: f64, scale_y: f64) -> Scale

Create a new Scale state based on the specified scale factors.

Use this constructor if the platform provided scale factor is the most accurate number.

pub fn dpi_x(&self) -> f64

Returns the x axis platform DPI associated with this Scale.

pub fn dpi_y(&self) -> f64

Returns the y axis platform DPI associated with this Scale.

pub fn scale_x(&self) -> f64

Returns the x axis scale factor.

pub fn scale_y(&self) -> f64

Returns the y axis scale factor.

pub fn to_px<T>(&self, item: &T) -> T where
    T: Scalable, 

Converts the item from display points into pixels, using the x axis scale factor for coordinates on the x axis and the y axis scale factor for coordinates on the y axis.

pub fn px_to_dp_x<T>(&self, x: T) -> f64 where
    T: Into<f64>, 

Converts from pixels into display points, using the x axis scale factor.

pub fn px_to_dp_y<T>(&self, y: T) -> f64 where
    T: Into<f64>, 

Converts from pixels into display points, using the y axis scale factor.

pub fn px_to_dp_xy<T>(&self, x: T, y: T) -> (f64, f64) where
    T: Into<f64>, 

Converts from pixels into display points, using the x axis scale factor for x and the y axis scale factor for y.

pub fn to_dp<T>(&self, item: &T) -> T where
    T: Scalable, 

Converts the item from pixels into display points, using the x axis scale factor for coordinates on the x axis and the y axis scale factor for coordinates on the y axis.

Trait Implementations

impl Clone for Scale

fn clone(&self) -> Scale

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Scale

impl Data for Scale

fn same(&self, other: &Self) -> bool

Determine whether two values are the same.

impl Debug for Scale

fn fmt(&self, f: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for Scale

fn default() -> Scale

Returns the "default value" for a type.

impl PartialEq<Scale> for Scale

fn eq(&self, other: &Scale) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Scale) -> bool

This method tests for !=.

impl StructuralPartialEq for Scale